I\'m trying to investigate a bug in a crash dump (so I can not change the code). I have a really complicated object (thousands of lines in the serialized representation) and
A variation on the answer from Omar Elabd --
It's not free, but there's a free trial for OzCode
 (https://marketplace.visualstudio.com/items?itemName=CodeValueLtd.OzCode).   
There's built-in exporting to JSON within the context/hover menu there, and it works a bit better than the Object Export extension (the trade-off for it not being free).
http://o.oz-code.com/features#export (demo)
I know this is a few years after the fact, but I'm leaving an answer here because this worked for me, and someone else may find it useful.