The bug
When you give yourself an item with the display tag with custom name, such as
/give @s minecraft:pumpkin{display:{Name:"ItemName"}}
the game crashes instantly and on the crash report the following error appears:
Description: Unexpected error
com.google.gson.JsonSyntaxException: com.google.gson.stream.MalformedJsonException: Use JsonReader.setLenient(true) to accept malformed JSON at line 1 column 1 path
Also, the world gets corrupted and it crashes when you try to play it.
Linked issues
Comments 4
Why is this command incorrect? It worked like that in previous versions.
Even if it's incorrect, the game shouldn't crash, but recognize the error when typing in the command.
NBT changes, display.Name and CustomName needs to be valid json strings as of 18w01a, the crashing is fixed for next snapshot though: MC-123782
Your command is incorrect.
Try