diff --git a/ets2panda/checker/ets/typeCheckingHelpers.cpp b/ets2panda/checker/ets/typeCheckingHelpers.cpp
index 6496cdb8ce75eb3a25d6fc59349a8ce4840f40fc..c225e9188dce53612c1132f2d7730ca733ba5c0f 100644
--- a/ets2panda/checker/ets/typeCheckingHelpers.cpp
+++ b/ets2panda/checker/ets/typeCheckingHelpers.cpp
@@ -731,7 +731,15 @@ Type *ETSChecker::GuaranteedTypeForUnionFieldAccess(ir::MemberExpression *member
     const auto &types = etsUnionType->ConstituentTypes();
     ArenaVector<checker::Type *> apparentTypes {ProgramAllocator()->Adapter()};
     const auto *prop = memberExpression->Property();
-    const auto &propertyName = prop->IsIdentifier() ? prop->AsIdentifier()->Name() : prop->AsStringLiteral()->Str();
+    util::StringView propertyName;
+    if (prop->IsIdentifier()) {
+        propertyName = prop->AsIdentifier()->Name();
+    } else if (prop->IsStringLiteral()) {
+        propertyName = prop->AsStringLiteral()->Str();
+    } else {
+        return GlobalTypeError();
+    }
+
     for (auto *type : types) {
         auto searchFlags = PropertySearchFlags::SEARCH_FIELD | PropertySearchFlags::SEARCH_METHOD |
                            PropertySearchFlags::SEARCH_IN_BASE;
diff --git a/ets2panda/test/ast/compiler/ets/union_field_access_2.ets b/ets2panda/test/ast/compiler/ets/union_field_access_2.ets
new file mode 100644
index 0000000000000000000000000000000000000000..f3810056329f128bf4653a78446cd05f6a3cd3c2
--- /dev/null
+++ b/ets2panda/test/ast/compiler/ets/union_field_access_2.ets
@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2025 Huawei Device Co., Ltd.
+ * 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.
+ */
+
+// ensure compiler doesn't crash when compiling invalid code.
+
+(a ? delete arguments==({: false, Float64Array: []}) : [ArrayBuffer[false]])
+
+/* @@? 18:1 Error TypeError: Indexed access is not supported for such expression type. */
+/* @@? 18:2 Error TypeError: Unresolved reference a */
+/* @@? 18:6 Error TypeError: Unresolved reference delete */
+/* @@? 18:13 Error SyntaxError: Unexpected token. */
+/* @@? 18:13 Error TypeError: Unresolved reference arguments */
+/* @@? 18:24 Error TypeError: need to specify target type for class composite */
+/* @@? 18:26 Error SyntaxError: Unexpected token. */
+/* @@? 18:28 Error SyntaxError: Unexpected token. */
+/* @@? 18:54 Error SyntaxError: Unexpected token, expected ')'. */
+/* @@? 18:76 Error SyntaxError: Unexpected token ')'. */