Index: src/ResolvExpr/CurrentObject.cc
===================================================================
--- src/ResolvExpr/CurrentObject.cc	(revision fcd0b9d7282c8c187cc0111baf35ab6d4fb846a2)
+++ src/ResolvExpr/CurrentObject.cc	(revision de57af9e217ccb4f8e44b5ca36bdf77c6f0fdc58)
@@ -925,6 +925,8 @@
 		if ( auto aggr = dynamic_cast< const BaseInstType * >( type ) ) {
 			if ( auto sit = dynamic_cast< const StructInstType * >( aggr ) ) {
+				assert( sit->base );
 				return new StructIterator{ loc, sit };
 			} else if ( auto uit = dynamic_cast< const UnionInstType * >( aggr ) ) {
+				assert( uit->base );
 				return new UnionIterator{ loc, uit };
 			} else {