mj_loadPluginLibrary should return the handle to the loaded library

[PeterOGB]

The feature, motivation and pitch

Currently mj_loadPluginLibrary returns void. It would be helpful if it returned the void * handle to the loaded library as returned by dlopen (Or the win32 equivalent) . This would allow applications to fail early if the library file is not found at the given location.

Alternatives

No response

Additional context

No response

[saran-t]

I'm open to this. Would you like us to implement it or do you want to send us a PR?

[jjyyxx]

@saran-t Also, I suggest that mj_loadPluginLibrary should log the error (from dlerror, etc.) to stderr if loading fails. The current behavior of returning silently is quite misleading (plus there is no Python API to check plugin status). Last time when my plugin fails to load (fault on my end due to incorrect linking flags, but quite subtle), I had to gdb into the mj_loadPluginLibrary function, run call dlerror() after dlopen(...) to get some hints.