ifcgeom: keep unopened geometry when opening subtraction throws a non-std::exception (#6391)

OCCT's Standard_Failure hierarchy does not derive from std::exception, so any
raw OCCT exception escaping convert_openings() lands in the generic catch (...)
handler rather than catch (const std::exception&). That handler logged the
error but never set caught_error, so the safety check right after (which
exists precisely to keep the product's unopened geometry when opening
processing fails) was bypassed and the incomplete/empty opened_shapes
silently replaced the product's solid geometry. The element ends up with zero
faces and disappears entirely from the viewport, matching "walls disappear
when a project is opened" (recalculating the wall regenerates a clean
representation that doesn't hit the same exception, which is why that
"fixes" it for the reporter).

Generated with the assistance of an AI coding tool.

src/ifcgeom/Converter.cpp

@@ -212,7 +212,9 @@ IfcGeom::BRepElement* ifcopenshell::geometry::Converter::create_brep_for_represe
 			logger_.Message(Logger::LOG_ERROR, "GEO", 33, std::string("Error processing openings for: ") + e.what() + ":", product);
 			caught_error = true;
 		} catch (...) {
+			// Non-std::exception (e.g. OCCT's Standard_Failure) also counts as caught_error.
 			logger_.Message(Logger::LOG_ERROR, "GEO", 34, "Error processing openings for:", product);
+			caught_error = true;
 		}
 
 		if (!(caught_error && opened_shapes.size() < shapes.size())) {