Poll not robust enough for F3 from nodeview.

[zeffii]

https://github.com/zeffii/mesh_tiny_cad/blob/5f9503f3382506769754b586db7e0520756f5500/BIX.py#L87-L90

error, though harmless

Traceback (most recent call last):
  File "C:\Users\zeffi\Desktop\test_blenders\current_28\2.82\scripts\addons\mesh_tiny_cad\BIX.py", line 90, in poll
    return all([obj is not None, obj.type == 'MESH', obj.mode == 'EDIT'])
AttributeError: 'NoneType' object has no attribute 'type'

location: <unknown location>:-1

[zeffii]

there is a scenario where the scene has no Objects yet, so no object is active. .. or the object has no .type