Remove unnecesary checks for falsiness.
Remove unnecesary checks for falsiness.

These checks are unnecessary because, whatever the falsy value
returned by `request.json`, it'll be one of those listed in the
right side of the table in https://docs.python.org/3/library/json.html#json-to-py-table
so it will be caught as invalid by `jsonschema`.

angelsanz/server,angelsanz/server,RemoteHelper/server,RemoteHelper/server