Error Handling

If a component decide it has an error it reply back to world on:

this.mountpoint.tasks().error(new TxTasks<..>(.. I have an error ..)

Then the job stop it current execution and start error handling sequence. It send error message to every already called components in a backward order.

for (every components already called n backward order) do:
    mountpoint.tasks().error(..)
done

This will called the error callback on every components which need to clean up its stuff.