What is the point of isError if there exists an error property in useQuery?

[lisherwin]

What is the point of isError is when there is already an error property in the return object of useQuery? It seems like everywhere we use isError, we can simply check for the existence of the error object instead. In fact, the existence check e.g. if (error) is something we'd probably need to do downstream as well even if we checked isError to get the more granular error message or error type. My team has been thinking of removing all isError in our codebase, but we're not sure if there are unintended consequences or advantages we've missed from doing so.

Thanks in advance!

[TkDodo]

a query has 3 states: pending, success, error. If it's in error state (the booleans are just derived from that status), error can no longer be null. You can use that check or not, it's up to you

[lisherwin]

Thanks!