fix(electron): Prevent promises both resolving and rejecting

[27pchrisl]

This change adds returns after all rejects, so that promises don't resolve after a rejection.

[jcesarmobile]

I've been reading and if you first reject a promise and then resolve it later, it won't have any effect. But also have read that it's recommended to return after reject to avoid extra code execution.

In this cases doesn't save much, but I'm going to merge anyway, thanks for the PR!

[27pchrisl]

Hi, I should have put this in the original ticket, but the specific way I ran into a problem was this code:

      this.NodeFS.stat(options.path, (err:any, stats:any) => {
        if(err)
          reject(err);    <== "err" exists, and so a rejection occured

        resolve({type: 'Not Available', size: stats.size, ctime: stats.ctimeMs, mtime: stats.mtimeMs, uri: lookupPath});    <== JS engine moves onto this line, where because of the err "stats" is undefined and so throws due to stats.size accessing a property of an undefined.
      });

[jcesarmobile]

Ah, yeah, in that case it was a bug. Good catch!