fix: Return size info when converting icon

[0xjac]

Closes #42

@develar I had the same problem as described in #42 with packaged app which had an icon with in the wrong 0x0 directory. This should return the right size for all formats (icns, ico, set).

[hanjukim]

@develar When will this be merged? I am having same problem.

[0xjac]

@hanjukim if it helps until this is merged, you can have a look at the fix I used here (assuming you are also using electron builder) which essentially fulfills the promise early and then goes over all the icon sizes to replace any size of 0 with an hard-coded value.

@develar I'm sure you're busy, but if there is anything I can do to assist with to merge this PR let me know. 🙂