Ensure all empty arrays return [] instead of null

[fedekunze]

Summary

Querying empty objects sometimes return null instead of the expected [].

Problem Definition

This seems to be a recurrent problem for our users as there are quite some issues regarding this: #4276, #4693, #3705, #4259, etc.

Proposal

Create a util function for arrays to always return [] when empty

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For Admin Use

• Not duplicate issue
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[RiccardoM]

@alexanderbez @fedekunze Hey guys I could implement this. What are your thoughts on how to go for it? Like a simple util function and call it where needed?

[alexanderbez]

@RiccardoM at first thought, the way to approach this is to actually go through each querier method and wherever we return an error, check if the result is nil and return an empty array/slice instead.

[tnachen]

@RiccardoM are you still planning to work on this?

[RiccardoM]

@tnachen yup, but wanted to wait for additional thought before starting the implementation. Also, I wanted to close #4922 before