diff --git a/ets2panda/checker/ets/helpers.cpp b/ets2panda/checker/ets/helpers.cpp
index 8216c753cdaba25610609691cbdcd42cbec13d33..a14db8776927437877751363f34f4564e150fb92 100644
--- a/ets2panda/checker/ets/helpers.cpp
+++ b/ets2panda/checker/ets/helpers.cpp
@@ -1807,6 +1807,10 @@ Type *ETSChecker::GetReferencedTypeBase(ir::Expression *name)
         return name->Check(this);
     }
 
+    if (name->IsLiteral()) {
+        return name->Check(this);
+    }
+
     ES2PANDA_ASSERT(name->IsIdentifier());
     if (name->AsIdentifier()->Variable() == nullptr) {
         // SUPPRESS_CSA_NEXTLINE(alpha.core.AllocatorETSCheckerHint)
diff --git a/ets2panda/checker/ets/typeCheckingHelpers.cpp b/ets2panda/checker/ets/typeCheckingHelpers.cpp
index 60298e8aebafa4f4e8e38054fc6856f5f422a131..534203ded5bac9a87d4b97ff82fd894fedc66d40 100644
--- a/ets2panda/checker/ets/typeCheckingHelpers.cpp
+++ b/ets2panda/checker/ets/typeCheckingHelpers.cpp
@@ -1197,7 +1197,8 @@ static auto IsNonArrayLiteral(ir::Expression *init)
         return true;
     }
 
-    if (init->TsType()->IsETSEnumType() && init->TsType()->AsETSEnumType()->NodeIsEnumLiteral(init)) {
+    if (init->TsType() != nullptr && init->TsType()->IsETSEnumType() &&
+        init->TsType()->AsETSEnumType()->NodeIsEnumLiteral(init)) {
         return true;
     }
     return false;
diff --git a/ets2panda/compiler/lowering/ets/defaultParametersInConstructorLowering.cpp b/ets2panda/compiler/lowering/ets/defaultParametersInConstructorLowering.cpp
index 1362d01997d8bcfe69a5c0aa6c894405b4124a70..5f71a7becde5865645818d97b9dcffbbf2035a3b 100644
--- a/ets2panda/compiler/lowering/ets/defaultParametersInConstructorLowering.cpp
+++ b/ets2panda/compiler/lowering/ets/defaultParametersInConstructorLowering.cpp
@@ -216,11 +216,13 @@ static void ExpandOptionalParameterAnnotationsToUnions(public_lib::Context *ctx,
     for (auto p : function->Params()) {
         auto param = p->AsETSParameterExpression();
         if (param->IsOptional() && param->Initializer() == nullptr) {
-            param->SetTypeAnnotation(util::NodeAllocator::ForceSetParent<ir::ETSUnionType>(
-                allocator,
-                ArenaVector<ir::TypeNode *>({param->TypeAnnotation(), allocator->New<ir::ETSUndefinedType>(allocator)},
-                                            allocator->Adapter()),
-                allocator));
+            ArenaVector<ir::TypeNode *> typeNodes(allocator->Adapter());
+            if (param->TypeAnnotation() != nullptr) {
+                typeNodes.emplace_back(param->TypeAnnotation());
+            }
+            typeNodes.emplace_back(allocator->New<ir::ETSUndefinedType>(allocator));
+            param->SetTypeAnnotation(
+                util::NodeAllocator::ForceSetParent<ir::ETSUnionType>(allocator, std::move(typeNodes), allocator));
             param->TypeAnnotation()->SetParent(param->Ident());
         }
     }
diff --git a/ets2panda/ir/ets/etsTypeReference.cpp b/ets2panda/ir/ets/etsTypeReference.cpp
index e659e054749883d7336b57ff580217943c49d5bd..b8d7c80ee796ff494e09ab28c19f0f1be1cc69bc 100644
--- a/ets2panda/ir/ets/etsTypeReference.cpp
+++ b/ets2panda/ir/ets/etsTypeReference.cpp
@@ -64,6 +64,7 @@ ir::Identifier *ETSTypeReference::BaseName() const
     if (baseName->IsIdentifier()) {
         return baseName->AsIdentifier();
     }
+
     if (baseName->IsTSQualifiedName()) {
         ir::TSQualifiedName *iter = baseName->AsTSQualifiedName();
 
@@ -72,12 +73,23 @@ ir::Identifier *ETSTypeReference::BaseName() const
         }
         return iter->Left()->AsIdentifier();
     }
-    ir::MemberExpression *iter = baseName->AsMemberExpression();
 
-    while (iter->Property()->IsMemberExpression()) {
-        iter = iter->Property()->AsMemberExpression();
+    if (baseName->IsMemberExpression()) {
+        ir::MemberExpression *iter = baseName->AsMemberExpression();
+
+        while (iter->Property()->IsMemberExpression()) {
+            iter = iter->Property()->AsMemberExpression();
+        }
+        return iter->Property()->AsIdentifier();
+    }
+
+    if (baseName->IsLiteral()) {
+        ES2PANDA_ASSERT(baseName->OriginalNode() != nullptr && baseName->OriginalNode()->IsIdentifier());
+        return baseName->OriginalNode()->AsIdentifier();
     }
-    return iter->Property()->AsIdentifier();
+
+    ES2PANDA_UNREACHABLE();
+    return nullptr;
 }
 
 void ETSTypeReference::Dump(ir::AstDumper *dumper) const
diff --git a/ets2panda/test/ast/compiler/ets/Const_Literal_As_TypeAnnotation_1.ets b/ets2panda/test/ast/compiler/ets/Const_Literal_As_TypeAnnotation_1.ets
new file mode 100644
index 0000000000000000000000000000000000000000..6bcecc08b108c82e890c26cca09adede03514cfd
--- /dev/null
+++ b/ets2panda/test/ast/compiler/ets/Const_Literal_As_TypeAnnotation_1.ets
@@ -0,0 +1,24 @@
+/*
+ * 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.
+ */
+
+const e = 123
+@interface Ajno {
+    b:e: string[][X (c + d)],%
+
+/* @@? 18:7 Error TypeError: Cannot find type 'e'. */
+/* @@? 18:17 Error SyntaxError: Unexpected token ']'. */
+/* @@? 18:29 Error SyntaxError: Unexpected token, expected ']'. */
+/* @@? 25:1 Error SyntaxError: Unexpected token 'end of stream'. */
+
diff --git a/ets2panda/test/ast/compiler/ets/Const_Literal_As_TypeAnnotation_2.ets b/ets2panda/test/ast/compiler/ets/Const_Literal_As_TypeAnnotation_2.ets
new file mode 100644
index 0000000000000000000000000000000000000000..733c4a5ea39287c5feff86ad9570d5792ccd1d8f
--- /dev/null
+++ b/ets2panda/test/ast/compiler/ets/Const_Literal_As_TypeAnnotation_2.ets
@@ -0,0 +1,24 @@
+/*
+ * 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.
+ */
+
+const e = true
+@interface Ajno {
+    b:e: string[][X (c + d)],%
+
+/* @@? 18:7 Error TypeError: Cannot find type 'e'. */
+/* @@? 18:17 Error SyntaxError: Unexpected token ']'. */
+/* @@? 18:29 Error SyntaxError: Unexpected token, expected ']'. */
+/* @@? 25:1 Error SyntaxError: Unexpected token 'end of stream'. */
+
diff --git a/ets2panda/test/ast/compiler/ets/negative_optional_constructor.ets b/ets2panda/test/ast/compiler/ets/negative_optional_constructor.ets
new file mode 100644
index 0000000000000000000000000000000000000000..f38f0c8d9deab4aa9c5463a0313c20dbb497607f
--- /dev/null
+++ b/ets2panda/test/ast/compiler/ets/negative_optional_constructor.ets
@@ -0,0 +1,27 @@
+/*
+ * 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 A {
+  constructor(buffer: ArrayBuffer, byteOffset?: number, length?V number);
+
+/* @@? 17:3 Error TypeError: No matching call signature for constructor */
+/* @@? 17:14 Error TypeError: Only abstract or native methods can't have body. */
+/* @@? 17:64 Error SyntaxError: Parameter declaration should have an explicit type annotation. */
+/* @@? 17:64 Error SyntaxError: Unexpected token, expected ',' or ')'. */
+/* @@? 17:65 Error SyntaxError: Field type annotation expected. */
+/* @@? 17:66 Error SyntaxError: number is a predefined type, cannot be used as an identifier */
+/* @@? 17:72 Error SyntaxError: Unexpected token ')'. */
+/* @@? 28:1 Error SyntaxError: Expected '}', got 'end of stream'. */
+
diff --git a/ets2panda/test/ast/compiler/ets/negative_typo_1.ets b/ets2panda/test/ast/compiler/ets/negative_typo_1.ets
new file mode 100644
index 0000000000000000000000000000000000000000..946b6b4974729224417dbc0a781eda7c5d92fd7f
--- /dev/null
+++ b/ets2panda/test/ast/compiler/ets/negative_typo_1.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.
+ */
+
+@interface Anno {
+  e: @ring[][] = [["a", (c +ue)]]
+}
+
+/* @@? 17:3 Error TypeError: Invalid annotation field type. Only numeric, boolean, string, enum, or arrays of these types are permitted for annotation fields. */
+/* @@? 17:13 Error TypeError: Cannot find type 'ring'. */
+/* @@? 17:18 Error TypeError: Invalid value for annotation field, expected a constant literal. */
+/* @@? 17:19 Error TypeError: Initializer has 2 elements, but tuple requires 0 */