Angular Observable reduce function error "Type 'true' is not assignable to type 'false'."

Issue

I have a code in which the memberships$ is an observable of objects that have a property "role". I want to use reduce function in order to traverse all of them, and if anyone's role is "Collector" I want to return value true. This is the code:

hasCollectorRole$: Observable<boolean> = this.memberships$.pipe(
    map(arr => {
      return arr.reduce((acc, val) => {
        if (val.role == "Collector") {
          acc = true;
        }
        return acc;
      }, false)
    })
  );

This is the error that I get on it:

Type 'true' is not assignable to type 'false'.

How do I fix this?

Solution

Try specifying the reducer's default value's type via:

arr.reduce(..., false as boolean)

Right now, it looks like TS thinks the type that should be returned is false, not boolean, and true is not assignable to type false.

Answered By - D M