Fix crash in update_bim_tool_props when selected type isn't a valid ifc_class

props.ifc_class is an EnumProperty whose items list only the element/space
types present in the model. Assigning element_type.is_a() crashed with
`enum "<class>" not found` when the selected element's type wasn't a member
(e.g. a raw IfcTypeProduct, or a stale item list mid-rebuild), aborting the
post-commit refresh.

Wrap the assignment in the same try/except TypeError guard already used for
the sibling relating_type_id assignments (added in 233cc344fa).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/bonsai/bonsai/bim/handler.py

@@ -151,7 +151,14 @@ def update_bim_tool_props():
                 return
 
             if is_bim_tool:
-                props.ifc_class = element_type.is_a()
+                try:
+                    props.ifc_class = element_type.is_a()
+                except TypeError:
+                    # ifc_class only lists element/space types present in the model, so an
+                    # unsupported type (e.g. a raw IfcTypeProduct) or a stale item list mid-
+                    # rebuild raises `enum "<class>" not found`. Skip rather than crash the
+                    # handler — it re-fires on the next selection and the panel resyncs.
+                    pass
 
             # Only assign when the target enum is the one that lists this type — otherwise
             # we hit `enum "<id>" not found in (...)` if the user selects an element of a