Fix access violations at compile time when debugging.

[ollydev]

These are only exceptions that get raised while debugging in lazarus:

• Added nil checks to TLapeType_String
• Removed extra pointer debugging, this causes bad stuff to happen which goes unnoticed when not running in a debugger. It's already in a try..except block so I assume it's pretty hacky. The AVar value is something random, but low like 4.

[ollydev]

A question, the reason of this PR is to successfully run scripts in Lazarus while debugging. A problem i'm running into is DoCheckInternal raises a external SIGSEGV here.

Is there any way to handle this more safely?

[nielsAD]

We could pass along memory boundaries (or pass an array instead of a pointer) to RunCode to determine if something is part of the script.

[nielsAD]

I decided to add a check to TLapeType_Pointer.VarToString rather than changing its output. Why did you add checks to the other functions, do you have example of where they caused issues? Or are they just precautionary?

[ollydev]

I just tested with your commit and it seems that it resolved the issues and the nil checks are no longer needed.

[ollydev]

Updated the commit. Added CodeLen parameter to RunCode so we can ensure DoCheckInternal doesn't check outside of the bytecode.

[nielsAD]

Thanks!