Fix leak on consteval exception in ReflectionClass::__toString()

Author: nikic

ext/reflection/php_reflection.c

@@ -373,6 +373,7 @@ static void _class_string(smart_str *str, zend_class_entry *ce, zval *obj, char
 		ZEND_HASH_FOREACH_STR_KEY_PTR(&ce->constants_table, key, c) {
 			_class_const_string(str, ZSTR_VAL(key), c, ZSTR_VAL(sub_indent));
 			if (UNEXPECTED(EG(exception))) {
+				zend_string_release(sub_indent);
 				return;
 			}
 		} ZEND_HASH_FOREACH_END();

ext/reflection/tests/ReflectionClass_toString_004.phpt

@@ -0,0 +1,17 @@
+--TEST--
+Constant evaluation exception during ReflectionClass::__toString()
+--FILE--
+<?php
+
+class A {
+    const C = self::UNKNOWN;
+}
+try {
+    echo new ReflectionClass(A::class);
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+?>
+--EXPECT--
+Undefined class constant 'self::UNKNOWN'