src/main/java/io/reactivex/Completable.java
@CheckReturnValue
    @NonNull
    @SchedulerSupport(SchedulerSupport.NONE)
    public static Completable error(final Throwable error) {
        ObjectHelper.requireNonNull(error, "error is null");
        return RxJavaPlugins.onAssembly(new CompletableError(error));
    }
@CheckReturnValue
    @NonNull
    @SchedulerSupport(SchedulerSupport.NONE)
    public static Completable error(final Throwable error) {
        ObjectHelper.requireNonNull(error, "error is null");
        return RxJavaPlugins.onAssembly(new CompletableError(error));
    }
Creates a Completable instance that emits the given Throwable exception to subscribers.
<p>
<img width="640" height="462" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/Completable.error.png" alt="">
<dl>
<dt><b>Scheduler:</b></dt>
<dd>{@code error} does not operate by default on a particular {@link Scheduler}.</dd>
</dl>
@param error the Throwable instance to emit, not null
@return the new Completable instance
@throws NullPointerException if error is null