Make sure C++ exceptions do not crash the Python interpreter

src/ifcwrap/IfcGeomWrapper.i

@@ -282,6 +282,9 @@
 			kernel.setValue(IfcGeom::Kernel::GV_PRECISION, precision);
 			
 			IfcGeom::BRepElement<double>* brep = kernel.create_brep_for_representation_and_product<double>(settings, representation, product);
+			if (!brep) {
+				throw IfcParse::IfcException("Failed to process shape");
+			}
 			if (settings.use_brep_data()) {
 				IfcGeom::SerializedElement<double>* serialization = new IfcGeom::SerializedElement<double>(*brep);
 				delete brep;

src/ifcwrap/IfcParseWrapper.i

@@ -100,6 +100,10 @@ namespace IfcUtil {
 }
 
 %typemap(out) std::pair<IfcUtil::ArgumentType, Argument*> {
+	// The SWIG %exception directive does not take care
+	// of our typemap. So the argument conversion block
+	// is wrapped in a try-catch block manually.
+	try {
 	const Argument& arg = *($1.second);
 	const IfcUtil::ArgumentType type = $1.first;
 	if (arg.isNull() || type == IfcUtil::Argument_DERIVED) {
@@ -164,6 +168,11 @@ namespace IfcUtil {
 		break;
 	}
 	}
+	} catch(IfcParse::IfcException& e) {
+		SWIG_exception(SWIG_RuntimeError, e.what());
+	} catch(...) {
+		SWIG_exception(SWIG_RuntimeError, "An unknown error occurred");
+	}
 }
 
 %extend IfcParse::IfcFile {