CRDTs are modified even if onWrite raises an exception
When invoking an object method, the environment adds checks. These checks may raise an exception if there is a problem. Thus, before performing a write, checks must be done before modifying the CRDT. This will allow for example to check the writing rights if desired. So the developer can create his own environment to check what he wants before each write.
Currently, the CRDT is modified even if onWrite raises an exception.
We should also add tests to highlight these cases.