Correctly release values in Proxy.[[Get]] (#4477)

In Proxy.[[Get]] if the target.[[GetOwnPropertyDescriptor]] fails the
trap result should be freed.

Fixes: #4466

JerryScript-DCO-1.0-Signed-off-by: Peter Gal pgal.usz@partner.samsung.com

jerry-core/ecma/operations/ecma-proxy-object.c

@@ -1158,6 +1158,7 @@ ecma_proxy_object_get (ecma_object_t *obj_p, /**< proxy object */
   /* 12. */
   if (ECMA_IS_VALUE_ERROR (status))
   {
+    ecma_free_value (trap_result);
     return status;
   }
 

tests/jerry/es.next/regression-test-issue-4466.js

@@ -0,0 +1,35 @@
+// 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 called_get = false;
+var targetProxy = new Proxy({}, {
+  getOwnPropertyDescriptor: function(target, key) {
+    throw new URIError("Generate error");
+  }
+});
+
+var px = new Proxy(targetProxy, {
+  get: function(target, key) {
+    called_get = true;
+    return { debug: 1 };
+  }
+});
+
+try {
+  px.abc;
+  assert(false);
+} catch (ex) {
+  assert(ex instanceof URIError);
+  assert(called_get === true);
+}