Fix error messages for the JSON commands

Sometimes users receive other errors unlike Redis for JSON. In addition, error messages may vary depending on the version of the json path (V2 or legacy).

The errors are also different for `--jsonpathv2=true` and `--jsonpathv2=false`. This is unexpected behavior and should be fixed.

Start with the JSON commands and compare their error responses with Redis, checking both --jsonpathv2=true and --jsonpathv2=false as well as legacy and V2 JSONPath behavior. Done means equivalent errors no longer vary unexpectedly by JSONPath version or flag setting.

Written by the indexing model from the issue text.