diff --git a/ets2panda/checker/ets/typeCheckingHelpers.cpp b/ets2panda/checker/ets/typeCheckingHelpers.cpp
index dbc753ee3c1c88cf2c8d0a3643103271d49d368e..087c77677e4ea247e6ff02eb4d6bb0ab97a14510 100644
--- a/ets2panda/checker/ets/typeCheckingHelpers.cpp
+++ b/ets2panda/checker/ets/typeCheckingHelpers.cpp
@@ -666,7 +666,11 @@ Type *ETSChecker::GuaranteedTypeForUnionFieldAccess(ir::MemberExpression *member
 {
     const auto &types = etsUnionType->ConstituentTypes();
     ArenaVector<checker::Type *> apparentTypes {Allocator()->Adapter()};
-    const auto &propertyName = memberExpression->Property()->AsIdentifier()->Name();
+    const auto *prop = memberExpression->Property();
+    if (!prop->IsIdentifier() && !prop->IsStringLiteral()) {
+        return GlobalTypeError();
+    }
+    const auto &propertyName = prop->IsIdentifier() ? prop->AsIdentifier()->Name() : prop->AsStringLiteral()->Str();
     for (auto *type : types) {
         auto searchFlags = PropertySearchFlags::SEARCH_FIELD | PropertySearchFlags::SEARCH_METHOD |
                            PropertySearchFlags::SEARCH_IN_BASE;
diff --git a/ets2panda/checker/types/typeError.h b/ets2panda/checker/types/typeError.h
index 9b2d87c4075983d6df1c4a553fad6b2c8f7b3a55..86f49b40cce7ce36b426c122935ace1da5a8d4e6 100644
--- a/ets2panda/checker/types/typeError.h
+++ b/ets2panda/checker/types/typeError.h
@@ -42,6 +42,12 @@ public:
     {
         ss << ERROR_TYPE;
     }
+
+    Type *Instantiate([[maybe_unused]] ArenaAllocator *allocator, [[maybe_unused]] TypeRelation *relation,
+                      [[maybe_unused]] GlobalTypesHolder *globalTypes) override
+    {
+        return this;
+    }
 };
 
 }  // namespace ark::es2panda::checker
diff --git a/ets2panda/test/ast/compiler/ets/forof_bad_type.ets b/ets2panda/test/ast/compiler/ets/forof_bad_type.ets
new file mode 100644
index 0000000000000000000000000000000000000000..1f20a9aece0f3212230314dabc6e0dc21983254d
--- /dev/null
+++ b/ets2panda/test/ast/compiler/ets/forof_bad_type.ets
@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2024-2025 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.
+ */
+
+declare class A<T> {
+    a: A<T>
+    foo(f: (a: FixedArray<Tadad> | A<T>[]) => void):void
+    bar():A<T>
+}
+
+new A<number>().bar().a.foo((x) => {
+    for (let e of x) {
+        console.log(e)
+    }
+})
+
+/* @@? 18:27 Error TypeError: Cannot find type 'Tadad'. */
diff --git a/ets2panda/test/ast/compiler/ets/union_access.ets b/ets2panda/test/ast/compiler/ets/union_access.ets
new file mode 100644
index 0000000000000000000000000000000000000000..8132d86e19c9da26c90e0bf86d3df80cd89125c8
--- /dev/null
+++ b/ets2panda/test/ast/compiler/ets/union_access.ets
@@ -0,0 +1,23 @@
+/*
+ * 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.
+ */
+
+class C{}
+class A{}
+
+function foo(x: A | C) {
+    x[x+1]
+}
+
+/* @@? 20:5 Error TypeError: Indexed access is not supported for such expression type. */
\ No newline at end of file