diff --git a/jerry-core/parser/js/js-parser-expr.c b/jerry-core/parser/js/js-parser-expr.c
index a9d4429ad..6093e162d 100644
--- a/jerry-core/parser/js/js-parser-expr.c
+++ b/jerry-core/parser/js/js-parser-expr.c
@@ -3080,7 +3080,10 @@ parser_pattern_get_target (parser_context_t *context_p, /**< context */
     }
     else
     {
-      JERRY_ASSERT (context_p->next_scanner_info_p->type == SCANNER_TYPE_INITIALIZER);
+      if (context_p->next_scanner_info_p->type != SCANNER_TYPE_INITIALIZER)
+      {
+        parser_raise_error (context_p, PARSER_ERR_INVALID_DESTRUCTURING_PATTERN);
+      }
       scanner_get_location (&start_location, context_p);
 
       scanner_set_location (context_p, &((scanner_location_info_t *) context_p->next_scanner_info_p)->location);
diff --git a/jerry-core/parser/js/js-parser.c b/jerry-core/parser/js/js-parser.c
index 9d7e488ab..59e037df0 100644
--- a/jerry-core/parser/js/js-parser.c
+++ b/jerry-core/parser/js/js-parser.c
@@ -1854,7 +1854,10 @@ parser_parse_function_arguments (parser_context_t *context_p, /**< context */
 
       if (context_p->next_scanner_info_p->source_p == context_p->source_p)
       {
-        JERRY_ASSERT (context_p->next_scanner_info_p->type == SCANNER_TYPE_INITIALIZER);
+        if (context_p->next_scanner_info_p->type != SCANNER_TYPE_INITIALIZER)
+        {
+          parser_raise_error (context_p, PARSER_ERR_INVALID_DESTRUCTURING_PATTERN);
+        }
 
         if (context_p->status_flags & PARSER_FUNCTION_HAS_REST_PARAM)
         {
diff --git a/tests/jerry/es.next/regression-test-issue-4016-4019.js b/tests/jerry/es.next/regression-test-issue-4016-4019.js
new file mode 100644
index 000000000..c0196b0e9
--- /dev/null
+++ b/tests/jerry/es.next/regression-test-issue-4016-4019.js
@@ -0,0 +1,32 @@
+// 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.
+
+function checkSyntax(str) {
+  try {
+    eval(str);
+    assert(false);
+  } catch (e) {
+    assert(e instanceof SyntaxError);
+  }
+}
+
+checkSyntax(`function a ([{ catch (e) {
+  eval("var e");
+} }])`);
+
+
+checkSyntax(`function a ({
+  catch (e) {
+  eval("var e");
+}})`);