fix leaks

dynamodb/expression.odin

@@ -440,7 +440,13 @@ parse_expression_attribute_values :: proc(request_body: []byte) -> (map[string]A
 	for key, val in values_obj {
 		attr, attr_ok := parse_attribute_value(val)
 		if !attr_ok {
-			continue
+			// Clean up already-parsed values before returning error
+			for k, &v in result {
+				attr_value_destroy(&v)
+				delete(k)
+			}
+			delete(result)
+			return make(map[string]Attribute_Value), false
 		}
 		result[strings.clone(key)] = attr
 	}