The error message is telling you that the file it’s mentioning is broken at line 1, column 1 (that’s what the :1:1 at the end of the filename means).
I don’t use that package but I just installed it to check, The default contents of that file for me are:
[
{ "keys": ["ctrl+alt+f"], "command": "code_formatter"}
]
Check your version of the file and see what it looks like; you might have an extra character in front of the [ character (or instead of it, etc). You can get to the file by opening the file named or by selecting Preferences > Package Settings > CodeFormatter > Key Bindings - Default
.
Note also that your version of the file might have more contents in it if you’ve added other key bindings.