tree c81593fa5c522a89c36eb8c7eb3e02338aada2a2
parent 376d418b1b535030fbe3369938d2ffdbb0340a77
author Nate Bosch <nbosch@google.com> 1614728408 -0800
committer Nate Bosch <nbosch@google.com> 1614730278 -0800

Use onError over catchError

`Future.catchError` is more error prone in null safe dart than `onError`
because return type of the `Function` callback is not statically
enforced and `null` was a common default value which no longer works.

Migrate all calls from `catchError` to `onError` to demonstrate best
practices. The other usages in this package are mostly on
`Future<dynamic>` and mostly look safe, though I can't rule out a type
error in unusual situations.

There was at least one mistake made in the migration of this library -
the code to ignore errors when completing a `CancelableOperation` as an
error after it was already canceled would instead cause a type error to
surface. Fix this and add a test.