Fixed bug in tool.Blender.get_bmesh_for_mesh

It caused errors because it was expecting mesh object to be selected - when it's not necessary that active_object is the one that mesh belongs to and sometimes no objects can be selected at all.

src/blenderbim/blenderbim/tool/blender.py

@@ -208,7 +208,7 @@ class Blender:
     def get_bmesh_for_mesh(cls, mesh, clean=False):
         import bmesh
 
-        if bpy.context.object.mode == "EDIT":
+        if mesh.is_editmode:
             bm = bmesh.from_edit_mesh(mesh)
             if clean:
                 bm.clear()