Fix exception when trying to introduce a variable for expression of undeclared type

src/EditorFeatures/CSharpTest/CodeActions/IntroduceVariable/IntroduceVariableTests.cs

@@ -5930,5 +5930,23 @@ void Test()
 
             await TestInRegularAndScriptAsync(code, expected, index: 1);
         }
+
+        [WorkItem(30207, "http://github.com/dotnet/roslyn/issues/30207")]
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsIntroduceVariable)]
+        public async Task TestExpressionOfUndeclaredType()
+        {
+            var code =
+@"class C
+{
+    void Test()
+    {
+        A[] array = [|A|].Foo();
+        foreach (A a in array)
+        {
+        }
+    }
+}";
+            await TestMissingAsync(code);
+        }
     }
 }

src/EditorFeatures/VisualBasicTest/CodeActions/IntroduceVariable/IntroduceVariableTests.vb

@@ -3166,5 +3166,17 @@ End Class
 "
             Await TestInRegularAndScriptAsync(source, expected, index:=1)
         End Function
+
+        <Fact, Trait(Traits.Feature, Traits.Features.CodeActionsIntroduceVariable)>
+        <WorkItem(30207, "https://github.com/dotnet/roslyn/issues/30207")>
+        Public Async Function TestExpressionOfUndeclaredType() As Task
+            Dim source = "
+Class C
+    Sub Test        
+        Dim array As A() = [|A|].Bar()
+    End Sub
+End Class"
+            Await TestMissingAsync(source)
+        End Function
     End Class
 End Namespace

src/Features/Core/Portable/IntroduceVariable/AbstractIntroduceVariableService.State.cs

@@ -70,6 +70,12 @@ public State(TService service, SemanticDocument document)
                     return false;
                 }
 
+                var expressionType = this.Document.SemanticModel.GetTypeInfo(this.Expression, cancellationToken).Type;
+                if (expressionType is IErrorTypeSymbol)
+                {
+                    return false;
+                }
+
                 var containingType = this.Expression.AncestorsAndSelf()
                     .Select(n => this.Document.SemanticModel.GetDeclaredSymbol(n, cancellationToken))
                     .OfType<INamedTypeSymbol>()