diff --git a/runtime/tests/vm/dart/regress_49279_test.dart b/runtime/tests/vm/dart/regress_49279_test.dart
new file mode 100644
index 00000000000..78a3c34e630
--- /dev/null
+++ b/runtime/tests/vm/dart/regress_49279_test.dart
@@ -0,0 +1,13 @@
+// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// VMOptions=--null-assertions --no-sound-null-safety --enable-asserts
+
+void main() {
+  try {
+    null!;
+  } on TypeError {
+    // _CastError implements TypeError
+  }
+}
diff --git a/runtime/tests/vm/dart_2/regress_49279_test.dart b/runtime/tests/vm/dart_2/regress_49279_test.dart
new file mode 100644
index 00000000000..78a3c34e630
--- /dev/null
+++ b/runtime/tests/vm/dart_2/regress_49279_test.dart
@@ -0,0 +1,13 @@
+// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// VMOptions=--null-assertions --no-sound-null-safety --enable-asserts
+
+void main() {
+  try {
+    null!;
+  } on TypeError {
+    // _CastError implements TypeError
+  }
+}
diff --git a/sdk/lib/_internal/vm/lib/errors_patch.dart b/sdk/lib/_internal/vm/lib/errors_patch.dart
index 05b0afaa32b..91ce8acf18c 100644
--- a/sdk/lib/_internal/vm/lib/errors_patch.dart
+++ b/sdk/lib/_internal/vm/lib/errors_patch.dart
@@ -122,9 +122,9 @@ class _CastError extends Error implements CastError, TypeError {
   String toString() => _errorMsg;
 
   // Fields _url, _line, and _column are only used for debugging purposes.
-  final String _url;
-  final int _line;
-  final int _column;
+  final String? _url;
+  final int? _line;
+  final int? _column;
   final String _errorMsg;
 }