Add return types to subscriptionController file

[konstantinabl]

Problem

Return types for some functions in the subscriptionController file are missing

Solution

Add return types, where needed

Alternatives

No response

[quiet-node]

Could you please give me a little more context on this issue?

[konstantinabl]

@quiet-node
For example function below has no return type:

Should be like this:

Thats a good practice and it actually makes sense, since this is one of the reasons why typescript is used

[quiet-node]

Ah I see! Yes indeed that's a good practice!