Why not simply do a straight exit-early if+return?

  if(!username || username.trim() = '')
     return { error: "No Username Given.", field: 'name' };

  if(!password || password.trim() = '')
     return { error: "No Password Given.", field: 'password' };

and so on.

Is that not clever enough??? Even a monkey would understand this.

Why? The snippet of code is simple and functional enough to escape the need of being fiddled with ad infinitum ad absurdum. I can't see a cloud of maintenance need hovering over it.