So, was editing the json file for Shopkeepers because I wanted to add the new items (soul dew, assault vest, etc.). I had added the item ids in the NPC folder and ran it through a parser to check, all was well. Restarted my server to find all NPC Shopkeepers gone, when I tried to spawn one in Via NPC Editor tool, it kicked me out of the server. There was no crash thankfully. It was no formatting issue because if that occurs then no items appear in the shopkeepers inventory, so I personally believe it is a corrupted item ID. Could be wrong though. Just wanted to let the Devs know to find the fix, because I know of other server which added SOME of the new items but not all and their shopkeepers work perfectly.

Raw JSON formatting is not the only problem that can occur. Post console errors and any edited JSON files.

Just tried to recreated the bug, did not work out but here is the information you asked for earlier just in case you want to try yourself.

http://pastebin.com/8sL6tUvk

http://pastebin.com/bZ9f6Bss

http://pastebin.com/xNGwYA6F

You have the JSON file before and after it was edited, and the startup.