fix serialize success type

Author: rpmccarter

packages/mdx/src/types/index.ts

@@ -1,5 +1,5 @@
 import type { SerializeOptions, SerializeResult } from 'next-mdx-remote-client/serialize';
 
-type SerializeSuccess = Omit<SerializeResult, 'error'>;
+type SerializeSuccess = SerializeResult & { compiledSource: string };
 
 export type { SerializeOptions, SerializeResult, SerializeSuccess };