diff --git a/src/Kiota.Builder/Refiners/TypeScriptRefiner.cs b/src/Kiota.Builder/Refiners/TypeScriptRefiner.cs
index 6e9288a894..85f22e79e0 100644
--- a/src/Kiota.Builder/Refiners/TypeScriptRefiner.cs
+++ b/src/Kiota.Builder/Refiners/TypeScriptRefiner.cs
@@ -1493,28 +1493,22 @@ private static void AddDeserializerUsingToDiscriminatorFactory(CodeElement codeE
 
             foreach (var mappedType in parsableFactoryFunction.OriginalMethodParentClass.DiscriminatorInformation.DiscriminatorMappings)
             {
-                if (mappedType.Value is CodeType type && type.TypeDefinition is CodeClass mappedClass)
+                // check if the model was trimmed
+                if (mappedType.Value is CodeType type && type.TypeDefinition is CodeClass mappedClass && mappedClass.Parent is CodeNamespace codeNamespace && codeNamespace.FindChildByName<CodeClass>(mappedClass.Name) != null)
                 {
-                    try
-                    {
-                        var deserializer = GetSerializationFunctionsForNamespace(mappedClass).Item2;
+                    var deserializer = GetSerializationFunctionsForNamespace(mappedClass).Item2;
 
-                        if (deserializer.Parent is not null)
+                    if (deserializer.Parent is not null)
+                    {
+                        parsableFactoryFunction.AddUsing(new CodeUsing
                         {
-                            parsableFactoryFunction.AddUsing(new CodeUsing
+                            Name = deserializer.Parent.Name,
+                            Declaration = new CodeType
                             {
-                                Name = deserializer.Parent.Name,
-                                Declaration = new CodeType
-                                {
-                                    Name = deserializer.Name,
-                                    TypeDefinition = deserializer
-                                },
-                            });
-                        }
-                    }
-                    catch (InvalidOperationException)
-                    {
-                        // The deserializer function for the mapped class does not exist.
+                                Name = deserializer.Name,
+                                TypeDefinition = deserializer
+                            },
+                        });
                     }
                 }
             }
diff --git a/src/Kiota.Builder/Writers/TypeScript/CodeConstantWriter.cs b/src/Kiota.Builder/Writers/TypeScript/CodeConstantWriter.cs
index 0abb0fda27..f9f41d41a8 100644
--- a/src/Kiota.Builder/Writers/TypeScript/CodeConstantWriter.cs
+++ b/src/Kiota.Builder/Writers/TypeScript/CodeConstantWriter.cs
@@ -169,7 +169,7 @@ private string GetTypeFactory(bool isVoid, bool isStream, CodeMethod codeElement
     {
         if (isVoid) return string.Empty;
         var typeName = conventions.TranslateType(codeElement.ReturnType);
-        if (isStream || IsPrimitiveType(typeName)) return $" \"{typeName}\"";
+        if (isStream || IsPrimitiveType(typeName) || IsKiotaPrimitive(typeName)) return $" \"{typeName}\"";
         if (GetPrimitiveAlias(typeName) is { } alias && !string.IsNullOrEmpty(alias))
             return $" \"{alias}\"";
         return $" {GetFactoryMethodName(codeElement.ReturnType, codeElement, writer)}";