On IW4-SP and IW4x you can obtain extended error messages from the GSC VM by setting the developer and developer_script dvar to 1 respectively.
This means a few things:
- When you get a compilation error you will know exactly which file and at which line/column the error is.
- When you get a runtime error you will have a complete stack trace showing from which function the error originated (file name and line/column) and the call stack showing the caller of the function (file name and line/column).
These messages can be accessed by opening the console with ~, if you run IW4x with the -stdout command line option you will also see the messages in the external console. You can also access the log file from the userraw folder which contains a copy of these messages.
You can learn more about the command line options from here
IW5/IW6/S1/T7
The same applies to these clients. However, the quality of these extended error messages will not be the same as the original because the developers precompiled their game scripts, resulting in a loss of a lot of information at compile time. Extended error messages only apply to custom scripts compiled by the client.
On T7, this may differ significantly.
You need to set the developer and developer_script Dvars to 1. The information you receive on these clients will be limited compared to IW4x because the GSC VM changed significantly in later CoD titles.