Cosmos-sdk: empty rewards returns null

[fedekunze]

Summary of Bug

empty rewards from GET distribution/delegators/{delegatorAddress}/rewards should return [] instead of null

---

For Admin Use

• [ ] Not duplicate issue
• [ ] Appropriate labels applied
• [ ] Appropriate contributors tagged
• [ ] Contributor assigned/self-assigned

[faboweb]

It also crashes for empty validator rewards:

GET distribution/delegators/{delegatorAddress}/rewards/{validatorAddress}

{"message":"ABCIQuery: Response error: RPC error -32603 - Internal error: runtime error: invalid memory address or nil pointer dereference"}

[alexanderbez]

Yeah I remember making a comment about this during the distribution REST/CLI PR. It's fixable, we just need some custom result handling logic -- nothing major.

[jackzampolin]

@fedekunze Are there any other endpoints that exhibit this behavior? I would imagine yes. Ideally we fix all these in 1 PR. Also should it return a 404 instead of []?

[faboweb]

I think [] needs less logic client side to handle the response.

[alexanderbez]

@faboweb what you're describing was fixed in #4047.