In that _specific_ example, I think the key part is the "... is not assignable to ServerRoute | ServerRoute[]". It's just giving you all the fields in the type of the object you _are_ returning, and trying to tell you "I can't go from an A to a B". But yes, hard to pick out the key bits of info in there.
In that _specific_ example, I think the key part is the "... is not assignable to ServerRoute | ServerRoute[]". It's just giving you all the fields in the type of the object you _are_ returning, and trying to tell you "I can't go from an A to a B". But yes, hard to pick out the key bits of info in there.