src/main/java/io/reactivex/internal/observers/DeferredScalarDisposable.java
public final void error(Throwable t) {
        int state = get();
        if ((state & (FUSED_READY | FUSED_CONSUMED | TERMINATED | DISPOSED)) != 0) {
            RxJavaPlugins.onError(t);
            return;
        }
        lazySet(TERMINATED);
        downstream.onError(t);
    }
public final void error(Throwable t) {
        int state = get();
        if ((state & (FUSED_READY | FUSED_CONSUMED | TERMINATED | DISPOSED)) != 0) {
            RxJavaPlugins.onError(t);
            return;
        }
        lazySet(TERMINATED);
        downstream.onError(t);
    }
Complete the target with an error signal.
@param t the Throwable to signal, not null (not verified)