[Patch] StreamIO crashes in Close()

Summary

Closing a file used with StreamIO crashes

System Information

• Operating system: macOS Ventura 13.6
• Processor architecture: x86-64
• Compiler version: trunk 1e64126f
• Device: computer

Steps to reproduce

Run test-case:

program TestStreamIOCrash;

{$mode objfpc}{$H+}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  Classes,
  streamIO;

var
  ms: TMemoryStream;
  F: TextFile;
begin
  ms:= TMemoryStream.Create;
  try
    FillChar(F, SizeOf(F), $80); //make sure this crashes
    AssignStream(F, ms);
    Rewrite(F);
    try
      Write(F, 'Close will crash');
    finally
      Close(F);
    end;
  finally
    ms.Free;
  end;
end.

What is the current bug behavior?

Crashes in Close()

What is the expected (correct) behavior?

Should not crash.

Possible fixes

AssignStream must initialise "new" TextRec.FullName string.