Fix value release in vm_loop for Proxy for-in cases (#3874)

Fixes #3868

JerryScript-DCO-1.0-Signed-off-by: Adam Szilagyi [email protected]

Author: szilagyiadam

jerry-core/vm/vm.c

@@ -3419,6 +3419,7 @@ vm_loop (vm_frame_ctx_t *frame_ctx_p) /**< frame context */
                        instruction.
                      - For other objects we should keep the current implementation due to performance reasons.*/
             result = ecma_raise_type_error (ECMA_ERR_MSG ("UNIMPLEMENTED: Proxy support in for-in."));
+            ecma_free_value (value);
             goto error;
           }
 #endif /* ENABLED (JERRY_ES2015_BUILTIN_PROXY) */

tests/jerry/es2015/regression-test-issue-3868.js

@@ -0,0 +1,22 @@
+// Copyright JS Foundation and other contributors, http://js.foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+var a = new Proxy({}, {});
+
+try {
+  for (var $ in a);
+  assert(false);
+} catch (e) {
+  assert(e instanceof TypeError);
+}