"blah" : "blah", // this comment is highlighted correctly
"blah" : "blah" // this comment has a red space before it
when a key value pair has a comment on it the comment is only displayed correctly if there is a comma present. if there is no comma then the space immediately before the // of the comment is displayed in red indicating a syntax error where there is none (other than comments like this are not actually supported in json : )
I think this is always valid since the very first ST release because ST uses it as it’s settings file format… Or at least, it works at this moment in ST4.
the only “official” way of adding comments to json files is to create a comment structure item that physically takes up space in the structure you are defining. a comment is supposed to produce ZERO output but json comments per the standard DO produce output.
Pretty much everyone doing json parsers have added an unofficial // as a comment. the bug is related to this comment on non blank lines. if that line has a comma on the end the syntax highlighting is fine. if not there is a glitch.
p.s. what is ST4 ? I thougt ST3 was the latest
ST4:
You can find ST4 on the official discord chat server: https://discord.gg/HcmwdVK
You can only test with a valid license since they are all dev builds at this moment.
Issue confirmed in ST3211, but it no longer receives any update.
Probably had been fixed by https://github.com/sublimehq/Packages/pull/2194, which was not included in 3211.
i can wait patiently for the release of ST4 where it seems to be fixed 
I only discovered this because i wrote my own json parser for my curses library (not related to ncurses) allowing for user interface layout via json