Avoid split for undefined objects

lib/serializer.ts

@@ -241,6 +241,7 @@ function base64UrlToByteArray(str: string): Uint8Array | undefined {
 function splitSerializeName(prop: string): Array<string> {
   const classes: Array<string> = [];
   let partialclass = "";
+  if (prop) {
     const subwords = prop.split(".");
 
     for (const item of subwords) {
@@ -252,6 +253,7 @@ function splitSerializeName(prop: string): Array<string> {
         partialclass = "";
       }
     }
+  }
 
   return classes;
 }
@@ -533,7 +535,7 @@ function deserializeCompositeType(serializer: Serializer, mapper: CompositeMappe
     const propertyMapper = modelProps[key];
     const { serializedName, xmlName, xmlElementName } = propertyMapper;
     let propertyObjectName = objectName;
-    if (serializedName !== "") {
+    if (serializedName !== "" && serializedName !== undefined) {
       propertyObjectName = objectName + "." + serializedName;
     }