Merge pull request #5653 from smoke-y/emptyParen

Fix compiler segfault when trying to use () as type

src/checker.cpp

@@ -1797,6 +1797,9 @@ gb_internal void add_type_and_value(CheckerContext *ctx, Ast *expr, AddressingMo
 		}
 
 		expr = unparen_expr(expr);
+		if (expr == nullptr) {
+			break;
+		};
 	}
 	mutex_unlock(mutex);
 }