How to read a text file in Visual Studio 2019?

Edit: After someone pointed out I was trying to double my directory searching (is that the term to be used?), I corrected it and did a little bit of searching. For anyone else who may find this, here's my current code, which has given me the results I need:

Private Sub ExportCompiledModFileToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles ExportCompiledModFileToolStripMenuItem.Click
        Dim folderPath As String = CurrentProjectPath
        Dim BlockJSON As System.IO.StreamWriter
        BlockJSON = My.Computer.FileSystem.OpenTextFileWriter(folderPath + "\Export\Data\Objects\Database\ShapeSets\modded_blocks.json", True)
        BlockJSON.Close()
        lstFiles.Items.Clear()
        For Each i In My.Computer.FileSystem.GetFiles(CurrentProjectPath + "\ProjectData\blocks")
            lstFiles.Items.Add(i)
            Dim CurrentFile As String
            CurrentFile = My.Computer.FileSystem.ReadAllText(i)
            BlockJSON = My.Computer.FileSystem.OpenTextFileWriter(folderPath + "\Export\Data\Objects\Database\ShapeSets\modded_blocks.json", True)
            BlockJSON.WriteLine(CurrentFile)
            BlockJSON.Close()
            MsgBox(CurrentFile)

        Next
    End Sub

So I'm trying to read a text file line by line in Visual Studio for a tool, but no matter what I do, I can't get the text from inside the file. Here's the code I'm currently using. Yes, it has a custom extension, but it's a simple text file, which CAN be written to without any extension renaming.

Private Sub ExportCompiledModFileToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles ExportCompiledModFileToolStripMenuItem.Click
        Dim folderPath As String = CurrentProjectPath
        Dim BlockJSON As System.IO.StreamWriter
        BlockJSON = My.Computer.FileSystem.OpenTextFileWriter(folderPath + "\Export\Data\Objects\Database\ShapeSets\modded_blocks.json", True)
        BlockJSON.Close()
        lstFiles.Items.Clear()
        For Each i In My.Computer.FileSystem.GetFiles(CurrentProjectPath + "\ProjectData\blocks")
            lstFiles.Items.Add(i)
            Dim line As String
            Dim CurrentFile As System.IO.StreamReader
            CurrentFile = My.Computer.FileSystem.OpenTextFileReader(CurrentProjectPath + "\ProjectData\blocks" + i + ".smblock")
            BlockJSON = My.Computer.FileSystem.OpenTextFileWriter(folderPath + "\Export\Data\Objects\Database\ShapeSets\modded_blocks.json", True)
            CurrentFile.ReadToEnd()
            BlockJSON.WriteLine(CurrentFile)
            BlockJSON.Close()
            CurrentFile.Close()

        Next
    End Sub

But every time I press my Export button, I get this error:

System.NotSupportedException
  HResult=0x80131515
  Message=The given path's format is not supported.
  Source=mscorlib
  StackTrace:
   at System.Security.Permissions.FileIOPermission.EmulateFileIOPermissionChecks(String fullPath)
   at System.Security.Permissions.FileIOPermission.QuickDemand(FileIOPermissionAccess access, String fullPath, Boolean checkForDuplicates, Boolean needFullPath)
   at Microsoft.VisualBasic.FileIO.FileSystem.NormalizePath(String Path)
   at Microsoft.VisualBasic.FileIO.FileSystem.OpenTextFileReader(String file, Encoding encoding)
   at Microsoft.VisualBasic.MyServices.FileSystemProxy.OpenTextFileReader(String file)
   at Scrap_Mechanic_Mod_Creator.frmManualInstall.ExportCompiledModFileToolStripMenuItem_Click(Object sender, EventArgs e) in C:\Users\dagam\source\repos\Scrap Mechanic Mod Creator\Form2.vb:line 20
   at System.Windows.Forms.ToolStripItem.RaiseEvent(Object key, EventArgs e)
   at System.Windows.Forms.ToolStripMenuItem.OnClick(EventArgs e)
   at System.Windows.Forms.ToolStripItem.HandleClick(EventArgs e)
   at System.Windows.Forms.ToolStripItem.HandleMouseUp(MouseEventArgs e)
   at System.Windows.Forms.ToolStripItem.FireEventInteractive(EventArgs e, ToolStripItemEventType met)
   at System.Windows.Forms.ToolStripItem.FireEvent(EventArgs e, ToolStripItemEventType met)
   at System.Windows.Forms.ToolStrip.OnMouseUp(MouseEventArgs mea)
   at System.Windows.Forms.ToolStripDropDown.OnMouseUp(MouseEventArgs mea)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
   at System.Windows.Forms.ToolStrip.WndProc(Message& m)
   at System.Windows.Forms.ToolStripDropDown.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
   at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
   at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
   at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()
   at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()
   at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine)
   at Scrap_Mechanic_Mod_Creator.My.MyApplication.Main(String[] Args) in :line 81

  This exception was originally thrown at this call stack:
    System.Security.Permissions.FileIOPermission.EmulateFileIOPermissionChecks(string)
    System.Security.Permissions.FileIOPermission.QuickDemand(System.Security.Permissions.FileIOPermissionAccess, string, bool, bool)
    Microsoft.VisualBasic.FileIO.FileSystem.NormalizePath(string)
    Microsoft.VisualBasic.FileIO.FileSystem.OpenTextFileReader(string, System.Text.Encoding)
    Microsoft.VisualBasic.MyServices.FileSystemProxy.OpenTextFileReader(string)
    Scrap_Mechanic_Mod_Creator.frmManualInstall.ExportCompiledModFileToolStripMenuItem_Click(Object, System.EventArgs) in Form2.vb
    System.Windows.Forms.ToolStripItem.RaiseEvent(object, System.EventArgs)
    System.Windows.Forms.ToolStripMenuItem.OnClick(System.EventArgs)
    System.Windows.Forms.ToolStripItem.HandleClick(System.EventArgs)
    System.Windows.Forms.ToolStripItem.HandleMouseUp(System.Windows.Forms.MouseEventArgs)
    ...
    [Call Stack Truncated]

I've tried many ways from multiple videos and sites, including this one. If any one can help, that would be great! ~Erin Rose

It looks like you want to append the lines from all the files to your BlockJSON file?

See if something like this will simplify life:

Dim path As String = System.IO.Path.Combine(CurrentProjectPath, "ProjectData\blocks")
Dim JSON_path As String = System.IO.Path.Combine(folderPath, "Export\Data\Objects\Database\ShapeSets\modded_blocks.json")
Using BlockJSON As New StreamWriter(JSON_path, False)
    BlockJSON.BaseStream.SetLength(0) ' make sure everything is cleared out and gets overwritten
    For Each fi As FileInfo In New DirectoryInfo(path).GetFiles
        lstFiles.Items.Add(fi.Name)
        For Each line As String In System.IO.File.ReadAllLines(fi.FullName)
            BlockJSON.WriteLine(line)
        Next
    Next
End Using