Have a nicer error message when updating stubs fails due to insufficient permissions

[myrsloik]

c:\vapoursynth>vsrepo.py install bs
Rebuilding dist-info dirs for other python package installers
Fetching: https://github.com/vapoursynth/bestsource/releases/download/R16/BestSource-R16-VS-only-ci.7z
Successfully installed BestSource R16
Updating VapourSynth stubs
Traceback (most recent call last):
  File "C:\Program Files\VapourSynth\vsrepo\vsrepo.py", line 927, in <module>
    update_genstubs()
    ~~~~~~~~~~~~~~~^^
  File "C:\Program Files\VapourSynth\vsrepo\vsrepo.py", line 867, in update_genstubs
    genstubs4([])
    ~~~~~~~~~^^^^
  File "C:\Program Files\VapourSynth\vsrepo\vsgenstubs4\init.py", line 609, in main
    output_stubs(args, cores, list(implementations), list(instances))
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Program Files\VapourSynth\vsrepo\vsgenstubs4\init.py", line 510, in output_stubs
    stubs_path = locate_or_create_stub_file()
  File "C:\Program Files\VapourSynth\vsrepo\vsgenstubs4\init.py", line 421, in locate_or_create_stub_file
    makedirs(stub_dir)
    ~~~~~~~~^^^^^^^^^^
  File "<frozen os>", line 236, in makedirs
PermissionError: [WinError 5] Access is denied: 'C:\\Program Files\\Python314\\Lib\\site-packages\\vapoursynth-stubs'

[theChaosCoder]

Same problem on linux too.