Roblox Exploit in WPF | Monaco Error | Unable to execute javascript at this time, scripts can only be executed within a V8Context

Hello,

So, I have made a Roblox exploit in WPF in Visual Studio 2019. I have a basic UI, and I have decided to implement Monaco to it. The only problem is, I get the error:

Unable to execute javascript at this time, scripts can only be executed within a V8Context.

Full Exception:

System.Exception HResult=0x80131500 Message=Unable to execute javascript at this time, scripts can only be executed within a V8Context. Use the IWebBrowser.CanExecuteJavascriptInMainFrame property to guard against this exception. See https://github.com/cefsharp/CefSharp/wiki/General-Usage#when-can-i-start-executing-javascript for more details on when you can execute javascript. For frames that do not contain Javascript then no V8Context will be created. Executing a script once the frame has loaded it's possible to create a V8Context. You can use browser.GetMainFrame().ExecuteJavaScriptAsync(script) or browser.GetMainFrame().EvaluateScriptAsync to bypass these checks (advanced users only). Source=CefSharp StackTrace: at CefSharp.WebBrowserExtensions.ExecuteScriptAsync(IWebBrowser browser, String script) at RoSlasher_UI_WPF.Monaco.SetTheme(MonacoTheme theme) at RoSlasher_UI_WPF.MainWindow.d__5.MoveNext() at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<>c.b__6_1(Object state) at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context(Object state) at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx) at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem() at System.Threading.ThreadPoolWorkQueue.Dispatch() at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()

This exception was originally thrown at this call stack:

CefSharp.WebBrowserExtensions.ExecuteScriptAsync(CefSharp.IWebBrowser, string) RoSlasher_UI_WPF.Monaco.SetTheme(RoSlasher_UI_WPF.MonacoTheme) RoSlasher_UI_WPF.MainWindow.Browser_MonacoReady() System.Runtime.CompilerServices.AsyncMethodBuilderCore.ThrowAsync.AnonymousMethod__6_1(object) System.Threading.QueueUserWorkItemCallback.WaitCallback_Context(object) System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, object, bool) System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, object, bool) System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem() System.Threading.ThreadPoolWorkQueue.Dispatch() System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()

Considering the exception says that the only error in MainWindow.xaml.cs is the Browser_MonacoReady(), I will just post that part of the scripts else I won't be able to submit this post due to the characters of this message being too long.

MainWindow.xaml.cs (Browser_MonacoReady())

private async void Browser_MonacoReady()
        {
            Browser.SetTheme(MonacoTheme.Dark);
            Browser.SetText("");

            /* Intellisense */

            var KeywordsControlFlow = new List<string>
            {
                "and", "do", "elseif",
                "for", "function", "if",
                "in", "local", "not", "or",
                "then", "until", "while"
            };

            var KeywordsValue = new List<string>
            {
                "_G", "shared", "true", "false", "nil", "end",
                "break", "else", "repeat", "then", "return"
            };

            var IntellisenseNoDocs = new List<string>
            {
                "error", "getfenv", "getmetatable",
                "newproxy", "next", "pairs",
                "pcall", "print", "rawequal", "rawget", "rawset", "select", "setfenv",
                "tonumber", "tostring", "type", "unpack", "xpcall", "_G",
                "shared", "delay", "require", "spawn", "tick", "typeof", "wait", "warn",
                "game", "Enum", "script", "workspace"
            };

            foreach (var Key in KeywordsControlFlow)
            {
                Browser.AddIntellisense(Key, "Keyword", "", Key + " ");
            }

            foreach (var Key in KeywordsValue)
            {
                Browser.AddIntellisense(Key, "Keyword", "", Key);
            }

            foreach (var Key in IntellisenseNoDocs)
            {
                Browser.AddIntellisense(Key, "Method", "", Key);
            }

            Browser.AddIntellisense("hookfunction(<function> old, <function> hook)", "Method",
                "Hooks function 'old', replacing it with the function 'hook'. The old function is returned, you must use it to call the function further.",
                "hookfunction");
            Browser.AddIntellisense("getgenv(<void>)", "Method",
                "Returns the environment that will be applied to each script ran by RoSlasher.",
                "getgenv");
            Browser.AddIntellisense("keyrelease(<int> key)", "Method",
                "Releases 'key' on the keyboard. You can access the int key values on MSDN.",
                "keyrelease");
            Browser.AddIntellisense("setclipboard(<string> value)", "Method",
                "Sets 'value' to the clipboard.",
                "setclipboard");
            Browser.AddIntellisense("mouse2press(<void>)", "Method",
                "Clicks down on the right mouse button.",
                "mouse2press");
            Browser.AddIntellisense("getsenv(<LocalScript, ModuleScript> Script)", "Method",
                "Returns the environment of Script. Returns nil if the script is not running.",
                "getsenv");
            Browser.AddIntellisense("checkcaller(<void>)", "Method",
                "Returns true if the current thread was made by RoSlasher. Useful for metatable hooks.",
                "checkcaller");

            Browser.AddIntellisense("bit", "Class", "Bit Library", "bit");
            Browser.AddIntellisense("bit.bdiv(<uint> dividend, <uint> divisor)", "Method",
                "Divides 'dividend' by 'divisor', remainder is not returned.",
                "bit.bdiv");
            Browser.AddIntellisense("bit.badd(<uint> a, <uint> b)", "Method",
                "Adds 'a' with 'b', allows overflows (unlike normal Lua).",
                "bit.badd");
            Browser.AddIntellisense("bit.bsub(<uint> a, <uint> b)", "Method",
                "Subtracts 'a' with 'b', allows overflows (unlike normal Lua).",
                "bit.badd");
            Browser.AddIntellisense("bit.rshift(<uint> val, <uint> by)", "Method",
                "Does a right shift on 'val' using 'by'.",
                "bit.rshift");
            Browser.AddIntellisense("bit.band(<uint> val, <uint> by)", "Method",
                "Does a logical AND (&) on 'val' using 'by'.",
                "bit.band");
            Browser.AddIntellisense("bit.bor(<uint> val, <uint> by)", "Method",
                "Does a logical OR (|) on 'val' using 'by'.",
                "bit.bor");
            Browser.AddIntellisense("bit.bxor(<uint> val, <uint> by)", "Method",
                "Does a logical XOR (^) on 'val' using 'by'.",
                "bit.bxor");
            Browser.AddIntellisense("bit.bnot(<uint> val)", "Method",
                "Does a logical NOT on 'val'.",
                "bit.bnot");
            Browser.AddIntellisense("bit.bmul(<uint> val, <uint> by)", "Method",
                "Multiplies 'val' using 'by', allows overflows (unlike normal Lua)",
                "bit.bmul");
            Browser.AddIntellisense("bit.bswap(<uint> val)", "Method",
                "Does a bitwise swap on 'val'.",
                "bit.bswap");
            Browser.AddIntellisense("bit.tobit(<uint> val)", "Method",
                "Converts 'val' into proper form for bitwise operations.",
                "bit.tobit");
            Browser.AddIntellisense("bit.ror(<uint> val, <uint> by)", "Method",
                "Rotates right 'val' using 'by'.",
                "bit.ror");
            Browser.AddIntellisense("bit.lshift(<uint> val, <uint> by)", "Method",
                "Does a left shift on 'val' using 'by'.",
                "bit.lshift");
            Browser.AddIntellisense("bit.tohex(<uint> val)", "Method",
                "Converts 'val' to a hex string.",
                "bit.tohex");

            Browser.AddIntellisense("debug", "Class", "Debug Library", "debug");
            Browser.AddIntellisense("debug.getconstant(<function, int> fi, <int> idx)", "Method", "Returns the constant at index 'idx' in function 'fi' or level 'fi'.", "debug.getconstant");
            Browser.AddIntellisense("debug.profilebegin(<string> label>", "Method", "Opens a microprofiler label.", "debug.profilebegin");
            Browser.AddIntellisense("debug.profileend(<void>)", "Method", "Closes the top microprofiler label.", "debug.profileend");
            Browser.AddIntellisense("debug.traceback(<void>)", "Method", "Returns a traceback of the current stack as a string.", "debug.traceback");
            Browser.AddIntellisense("debug.getfenv(<T> o)", "Method", "Returns the environment of object 'o'.", "debug.getfenv");
            Browser.AddIntellisense("debug.getupvalue(<function, int> fi, <string> upval)", "Method", "Returns the upvalue with name 'upval' in function or level 'fi'.", "debug.getupvalue");
            Browser.AddIntellisense("debug.getlocals(<int> lvl)", "Method", "Returns a table containing the upvalues at level 'lvl'.", "debug.getlocals");
            Browser.AddIntellisense("debug.setmetatable(<T> o, <table> mt)", "Method", "Set the metatable of 'o' to 'mt'.", "debug.setmetatable");
            Browser.AddIntellisense("debug.getconstants(<function, int> fi)", "Method", "Retrieve the constants in function 'fi' or at level 'fi'.", "debug.getconstants");
            Browser.AddIntellisense("debug.getupvalues(<function, int> fi)", "Method", "Retrieve the upvalues in function 'fi' or at level 'fi'.", "debug.getupvalues");
            Browser.AddIntellisense("debug.setlocal(<int> lvl, <string> localname, <T> value)", "Method", "Set local 'localname' to value 'value' at level 'lvl'.", "debug.setlocal");
            Browser.AddIntellisense("debug.setupvalue(<function, int> fi, <string> upvname, <T> value)", "Method", "Set upvalue 'upvname' to value 'value' at level or function 'fi'.", "debug.setupvalue");
            Browser.AddIntellisense("debug.setconstant(<function, int> fi, <string> consname, <int, bool, nil, string> value)", "Method", "Set constant 'consname' to tuple 'value' at level or function 'fi'.", "debug.setupvalue");
            Browser.AddIntellisense("debug.getregistry(<void>)", "Method", "Returns the registry", "debug.getregistry");
            Browser.AddIntellisense("debug.getinfo(<function, int> fi, <string> w)", "Method", "Returns a table of info pertaining to the Lua function 'fi'.", "debug.getinfo");
            Browser.AddIntellisense("debug.getlocal(<int> lvl, <string> localname)", "Method", "Returns the local with name 'localname' in level 'lvl'.", "debug.getlocal");

            Browser.AddIntellisense("loadfile(<string> path)", "Method", "Loads in the contents of a file as a chunk and returns it if compilation is successful. Otherwise, if an error has occured during compilation, nil followed by the error message will be returned.", "loadfile");
            Browser.AddIntellisense("loadstring(<string> chunk, [<string> chunkname])", "Method", "Loads 'chunk' as a Lua function and returns it if compilation is succesful. Otherwise, if an error has occured during compilation, nil followed by the error message will be returned.", "loadstring");
            Browser.AddIntellisense("writefile(<string> filepath, <string> contents)", "Method", "Writes 'contents' to the supplied filepath.", "writefile");
            Browser.AddIntellisense("mousescroll(<signed int> px)", "Method", "Scrolls the mouse wheel virtually by 'px' pixels.", "mousescroll");
            Browser.AddIntellisense("mouse2click(<void>)", "Method", "Virtually presses the right mouse button.", "mouse2click");
            Browser.AddIntellisense("islclosure(<function> f)", "Method", "Returns true if 'f' is an LClosure", "islclosure");
            Browser.AddIntellisense("mouse1press(<void>)", "Method", "Simulates a left mouse button press without releasing it.", "mouse1press");
            Browser.AddIntellisense("mouse1release(<void>)", "Method", "Simulates a left mouse button release.", "mouse1release");
            Browser.AddIntellisense("keypress(<int> keycode)", "Method", "Simulates a key press for the specified keycode. For more information: https://docs.microsoft.com/en-us/windows/desktop/inputdev/virtual-key-codes", "keypress");
            Browser.AddIntellisense("mouse2release(<void>)", "Method", "Simulates a right mouse button release.", "mouse2release");
            Browser.AddIntellisense("newcclosure(<function> f)", "Method", "Pushes a new c closure that invokes function 'f' upon call. Used for metatable hooks.", "newcclosure");
            Browser.AddIntellisense("getinstances(<void>)", "Method", "Returns a list of all instances within the game.", "getinstances");
            Browser.AddIntellisense("getnilinstances(<void>)", "Method", "Returns a list of all instances parented to nil within the game.", "getnilinstances");
            Browser.AddIntellisense("readfile(<string> path)", "Method", "Reads the contents of the file located at 'path' and returns it. If the file does not exist, it errors.", "readfile");
            Browser.AddIntellisense("getscripts(<void>)", "Method", "Returns a list of all scripts within the game.", "getscripts");
            Browser.AddIntellisense("getrunningscripts(<void>)", "Method", "Returns a list of all scripts currently running.", "getrunningscripts");
            Browser.AddIntellisense("appendfile(<string> path, <string> content)", "Method", "Appends 'content' to the file contents at 'path'. If the file does not exist, it errors", "appendfile");
            Browser.AddIntellisense("listfiles(<string> folder)", "Method", "Returns a table of files in 'folder'.", "listfiles");
            Browser.AddIntellisense("isfile(<string> path)", "Method", "Returns if 'path' is a file or not.", "isfile");
            Browser.AddIntellisense("isfolder(<string> path)", "Method", "Returns if 'path' is a folder or not.", "isfolder");
            Browser.AddIntellisense("delfolder(<string> path)", "Method", "Deletes 'folder' in the workspace directory.", "delfolder");
            Browser.AddIntellisense("delfile(<string> path)", "Method", "Deletes 'file' from the workspace directory.", "delfile");
            Browser.AddIntellisense("getreg(<void>)", "Method", "Returns the Lua registry.", "getreg");
            Browser.AddIntellisense("getgc(<void>)", "Method", "Returns a copy of the Lua GC list.", "getgc");
            Browser.AddIntellisense("mouse1click(<void>)", "Method", "Simulates a full left mouse button press.", "mouse1click");
            Browser.AddIntellisense("getrawmetatable(<T> value)", "Method", "Retrieve the metatable of value irregardless of value's metatable's __metatable field. Returns nil if it doesn't exist.", "getrawmetatable");
            Browser.AddIntellisense("setreadonly(<table> table, <bool> ro)", "Method", "Sets table's read-only value to ro", "setreadonly");
            Browser.AddIntellisense("isreadonly(<table> table)", "Method", "Returns table's read-only condition.", "isreadonly");
            Browser.AddIntellisense("getrenv(<void>)", "Method", "Returns the global Roblox environment for the LocalScript state.", "getrenv");
            Browser.AddIntellisense("decompile(<LocalScript, ModuleScript, function> Script, bool Bytecode = false)", "Method", "Decompiles Script and returns the decompiled script. If the decompilation fails, then the return value will be an error message.", "decompile");
            Browser.AddIntellisense("dumpstring(<string> Script)", "Method", "Returns the Roblox formatted bytecode for source string 'Script'.", "dumpstring");
            Browser.AddIntellisense("getloadedmodules(<void>)", "Method", "Returns all ModuleScripts loaded in the game.", "getloadedmodules");
            Browser.AddIntellisense("isrbxactive(<void>)", "Method", "Returns if the Roblox window is in focus.", "getloadedmodules");
            Browser.AddIntellisense("getcallingscript(<void>)", "Method", "Gets the script that is calling this function.", "getcallingscript");
            Browser.AddIntellisense("setnonreplicatedproperty(<Instance> obj, <string> prop, <T> value)", "Method", "Sets the prop property of obj, not replicating to the server. Useful for anticheat bypasses.", "setnonreplicatedproperty");
            Browser.AddIntellisense("getconnections(<Signal> obj)", "Method", "Gets a list of connections to the specified signal. You can then use :Disable and :Enable on the connections to disable/enable them.", "getconnections");
            Browser.AddIntellisense("getspecialinfo(<Instance> obj)", "Method", "Gets a list of special properties for MeshParts, UnionOperations, and Terrain.", "getspecialinfo");
            Browser.AddIntellisense("messagebox(<string> message, <string> title, <int> options)", "Method", "Makes a MessageBox with 'message', 'title', and 'options' as options. See https://docs.microsoft.com/en-us/windows/desktop/api/winuser/nf-winuser-messagebox for more information.", "messagebox");
            Browser.AddIntellisense("messageboxasync(<string> message, <string> title, <int> options)", "Method", "Makes a MessageBox with 'message', 'title', and 'options' as options. See https://docs.microsoft.com/en-us/windows/desktop/api/winuser/nf-winuser-messagebox for more information.", "messageboxasync");
            Browser.AddIntellisense("rconsolename(<string> title)", "Method", "Sets the currently allocated console title to 'title'.", "rconsolename");
            Browser.AddIntellisense("rconsoleinput(<void>)", "Method", "Yields until the user inputs information into ther console. Returns the input the put in.", "rconsoleinput");
            Browser.AddIntellisense("rconsoleinputasync(<void>)", "Method", "Yields until the user inputs information into ther console. Returns the input the put in.", "rconsoleinputasync");
            Browser.AddIntellisense("rconsoleprint(<string> message)", "Method", "Prints 'message' into the console.", "rconsoleprint");
            Browser.AddIntellisense("rconsoleinfo(<string> message)", "Method", "Prints 'message' into the console, with a info text before it.", "rconsoleinfo");
            Browser.AddIntellisense("rconsolewarn(<string> message)", "Method", "Prints 'message' into the console, with a warning text before it.", "rconsolewarn");
            Browser.AddIntellisense("rconsoleerr(<string> message)", "Method", "Prints 'message' into the console, with a error text before it.", "rconsoleerr");
            Browser.AddIntellisense("fireclickdetector(<ClickDetector> detector, <number, nil> distance)", "Method", "Fires click detector 'detector' with 'distance'. If a distance is not provided, it will be 0.", "fireclickdetector");
            Browser.AddIntellisense("firetouchinterest(<Part> part, <TouchTransmitter> transmitter, <number> toggle)", "Method", "Fires touch 'transmitter' with 'part'. Use 0 to toggle it being touched, 1 for it not being toggled.", "firetouchinterest");
            Browser.AddIntellisense("saveinstance(<table> t)", "Method", "Saves the Roblox game into your workspace folder.", "saveinstance");

            await Task.Delay(250);
            Dispatcher.Invoke(() => { Browser.Opacity = 1; });
        }

Monaco.cs

using System;
using System.IO;
using System.Reflection;
using System.Windows;
using System.Windows.Input;
using CefSharp;
using CefSharp.Wpf;
using CefSharp.Wpf.Internals;

namespace RoSlasher_UI_WPF
{
    public enum MonacoTheme
    {
        Light = 0,
        Dark = 1
    }

    public class MonacoSettings
    {
        public bool ReadOnly; // The ability to edit text.
        public bool AutoIndent; // Enables auto indentation & adjustment
        public bool Folding; // Enables code folding.
        public bool FontLigatures; // Enables font ligatures.
        public bool Links;  // Enables whether links are clickable & detectible.
        public bool MinimapEnabled; // Enables whether code minimap is enabled.
        public int LineHeight; // Set's the line height.
        public double FontSize; // Determine's the font size of the text.
        public string FontFamily; // Set's the font family for the editor.
        public string RenderWhitespace; // "none" | "boundary" | "all"
    }

    public class Monaco : ChromiumWebBrowser
    {
        public bool MonacoLoaded;
        public delegate void MonacoReadyDelegate();

        public event MonacoReadyDelegate MonacoReady;

        public Monaco()
        {
            Opacity = 0;
            Address = $"file:///{Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location).Replace("\\", "/")}/Monaco.html";

            LoadingStateChanged += (sender, args) =>
            {
                if (args.IsLoading) return;

                MonacoLoaded = true;
                MonacoReady?.Invoke();
            };
        }

        protected override void OnMouseLeave(MouseEventArgs e)
        {
            e.Handled = true;

            var browser = GetBrowser();
            var modifiers = e.GetModifiers();
            var point = e.GetPosition(this);

            if (e.LeftButton == MouseButtonState.Pressed)
            {
                browser.GetHost().SendMouseClickEvent((int)point.X, (int)point.Y, MouseButtonType.Left, mouseUp: true, clickCount: 1, modifiers: modifiers);
            }

            browser.GetHost().SendMouseMoveEvent((int)point.X, (int)point.Y, true, modifiers);

            base.OnMouseLeave(e);
        }

        /// <summary>
        /// Set's Monaco editor's theme to the selected Choice.
        /// </summary>
        /// <param name="theme"></param>
        public void SetTheme(MonacoTheme theme)
        {
            if (!MonacoLoaded) return;

            switch (theme)
            {
                case MonacoTheme.Dark:
                    this.ExecuteScriptAsync("SetTheme", "Dark");
                    break;
                case MonacoTheme.Light:
                    this.ExecuteScriptAsync("SetTheme", "Light");
                    break;
                default:
                    throw new ArgumentOutOfRangeException(nameof(theme), theme, null);
            }
        }

        /// <summary>
        /// Set's the text of Monaco to the parameter text.
        /// </summary>
        /// <param name="text"></param>
        public void SetText(string text)
        {
            if (MonacoLoaded)
                this.ExecuteScriptAsync("SetText", text);
        }

        private object EvaluateScript(string script)
        {
            var Task = this.EvaluateScriptAsync(script);
            Task.Wait();
            var Resp = Task.Result;
            return Resp.Success ? Resp.Result ?? "" : Resp.Message;
        }

        /// <summary>
        /// Get's the text of Monaco and returns it.
        /// </summary>
        /// <returns></returns>
        public string GetText()
        {
            if (!MonacoLoaded) return "";

            return (string)EvaluateScript("GetText();");
        }

        /// <summary>
        /// Appends the text of Monaco with the parameter text.
        /// </summary>
        /// <param name="text"></param>
        public void AppendText(string text)
        {
            if (MonacoLoaded)
                SetText(GetText() + text);
        }

        public void GoToLine(int lineNumber)
        {
            if (MonacoLoaded)
                this.ExecuteScriptAsync("SetScroll", lineNumber);
        }

        /// <summary>
        /// Refreshes the Monaco editor.
        /// </summary>
        public void EditorRefresh()
        {
            if (MonacoLoaded)
                this.ExecuteScriptAsync("Refresh");
        }

        /// <summary>
        /// Updates Monaco editor's settings with it's parameter structure.
        /// </summary>
        /// <param name="settings"></param>
        public void UpdateSettings(MonacoSettings settings)
        {
            if (!MonacoLoaded) return;

            this.ExecuteScriptAsync("SwitchMinimap", settings.MinimapEnabled);
            this.ExecuteScriptAsync("SwitchReadonly", settings.ReadOnly);
            this.ExecuteScriptAsync("SwitchRenderWhitespace", settings.RenderWhitespace);
            this.ExecuteScriptAsync("SwitchLinks", settings.Links);
            this.ExecuteScriptAsync("SwitchLineHeight", settings.LineHeight);
            this.ExecuteScriptAsync("SwitchFontSize", settings.FontSize);
            this.ExecuteScriptAsync("SwitchFolding", settings.Folding);
            this.ExecuteScriptAsync("SwitchAutoIndent", settings.AutoIndent);
            this.ExecuteScriptAsync("SwitchFontFamily", settings.FontFamily);
            this.ExecuteScriptAsync("SwitchFontLigatures", settings.FontLigatures);
        }

        /// <summary>
        /// Adds intellisense for the specified type.
        /// </summary>
        /// <param name="label"></param>
        /// <param name="type"></param>
        /// <param name="description"></param>
        /// <param name="insert"></param>
        public void AddIntellisense(string label, string type, string description, string insert)
        {
            if (MonacoLoaded)
                this.ExecuteScriptAsync("AddIntellisense", label, type, description, insert);
        }

        /// <summary>
        /// Creates a syntax error symbol (squiggly red line) on the specific parameters in the editor.
        /// </summary>
        /// <param name="line"></param>
        /// <param name="column"></param>
        /// <param name="endLine"></param>
        /// <param name="endColumn"></param>
        /// <param name="message"></param>
        public void ShowSyntaxError(int line, int column, int endLine, int endColumn, string message)
        {
            if (MonacoLoaded)
                this.ExecuteScriptAsync("ShowErr", line, column, endLine, endColumn, message);
        }
    }
}

Can someone look through the code and see where the problem may be occurring please? I've tried looking myself but I can't seem to figure it out.