retryExchange: TS error: Type 'Error' is not assignable to type 'boolean'. ts(2345)

[frederikhors]

Using your usage example here for retryExchange I have an error in my TS implementation:

const retryOptions: {
    initialDelayMs: number;
    maxDelayMs: number;
    randomDelay: boolean;
    maxNumberAttempts: number;
    retryIf: (err: CombinedError) => Error;
}
Argument of type '{ initialDelayMs: number; maxDelayMs: number; randomDelay: boolean; maxNumberAttempts: number; retryIf: (err: CombinedError) => Error; }' is not assignable to parameter of type 'RetryExchangeOptions'.
  The types returned by 'retryIf(...)' are incompatible between these types.
    Type 'Error' is not assignable to type 'boolean'.ts(2345)

using it like this:

const retryOptions = {
  initialDelayMs: 1000,
  maxDelayMs: 15000,
  randomDelay: true,
  maxNumberAttempts: 2,
	retryIf: (err: CombinedError): boolean => err && err.networkError,
}

Am I wrong?

[kitten]

It's because you typed this as retryIf: (err: CombinedError) => Error but it expects a boolean return value. By the way, you likely don't want to duplicate types for larger objects like this and instead either rely on inference or the package's option type.

[frederikhors]

I fixed it like this but I don't like the last line (return err && err.networkError && true):

const retryOptions = {
  // ...
  retryIf: (err: CombinedError): boolean => {
    if (err.response) {
      // handle this
      return false;
    }
    if (err.networkError) {
      // handle this
    }
    return err && err.networkError && true;
  },
};

What do you think?

[JoviDeCroock]

!!(err & err.networkError) should evaluate to the same thing