dart:async

completeError abstract method

void completeError(Object error, [ StackTrace stackTrace ])

Complete future with an error.

Calling complete or completeError must not be done more than once.

Completing a future with an error indicates that an exception was thrown while trying to produce a value.

If error is null, it is replaced by a NullThrownError.

If error is a Future, the future itself is used as the error value. If you want to complete with the result of the future, you can use:

thisCompleter.complete(theFuture)

or if you only want to handle an error from the future:

theFuture.catchError(thisCompleter.completeError);

Source

void completeError(Object error, [StackTrace stackTrace]);