Could you clarify how checking for some environment variable set by Libdoc would be better or easier that just gracefully handling the situation where the environment variables you need during execution don't exist?

@pekkaklarck you were right. I found an easier solution which works in my case.

In the __init__ of my library I just check if the code was run by libdoc and just quit in that case:

if "libdoc.py" in sys.argv[0]:
    return

This is a simpler solution. Now I can load my environment in the init but still get the code completion in vscode.

Not sure how I got here ;-)

But, I also regularly get such requests for robotcode that the keywords for some library cannot be loaded correctly or dead processes remain when the library is loaded in robotcode, or ... or ... or ... because people don't know that their library has to be instantiated correctly when creating a libdoc to get the keywords and that the code has to be executed in the constructor of the library.
This is why the property BuiltIn().robot_running was introduced in one of the last Robot Framework versions. With this property you can query exactly this behaviour and only initialize your library/variable file correctly if Robot is actually running, which is not the case when generating the LibDoc.
The property BuiltIn().dry_run_active should also be mentioned.

For older RobotFramework versions I always refer to the undocumented check EXECUTION_CONTEXTS.current is not None which corresponds to the check of robot_running.

Both properties are not really described anywhere. Wouldn't that be a topic for the UserGuide?

This is the issue for creating these properties #4666

Mentioning these properties in the User Guide is a good idea. That should have been done already as part of #4666. I'm on mobile but try to remember to do that later. If you want to make sure it's not forgotten, please submit an issue.

@d-biehl thanks for your hint to these BuiltIn() methods. I will change my code to use them instead of my hacky version. ;)

@pekkaklarck did you allready create an issue about this? if not I can create one.

@d-biehl I didn't submit an issue so please go ahead and submit one. Even better if you can take a look where to add this information in the User Guide.