Currently you cannot have null as the value for a parameter in an RPC request. This seems a bit odd.
Suggest replacing isset() on line 530 with array_key_exists()
Can you provide a PR for this? From the description, it is hard to understand the desired change in behavior.
This issue can be closed as a duplicate of #3696.
Currently you cannot pass NULL as the value of a non-optional method parameter.
We'll close this once #3696 is merged.
Merge branch 'hotfix/3767'