Running with -f patch always exits with code 1

[doctordesh]

Hello,

I'm using your fantastic tool to run diffs in a refactoring project. Works wonders! Today though, I tried to use the patch format instead, and even on files that are equal the output is [] (which might be by design) but the exit code is always 1, regardless if there are problems or not.

> ./jd --version
jd version 1.7.1
> echo "{}" > file1.json
> echo "{}" > file2.json
> ./jd -f patch file1.json file2.json
[]
> echo $?
1
> ./jd file1.json file2.json
> echo $?
0

[doctordesh]

I would guess that this is the problem. You always create an empty slice. Which means that json.Marshal further down will at least output [].

Then the first and last if here will fail and cause os.Exit(1)