Deal with missing connections

Vivide throws an error when trying to push an update through the next view, but the viewis not available anymore (most of the time, because it was removed from DOM)

Right now, we detect such connections, but do not repair the `output-connections` list properly.

Start by tracing the code that pushes an update through the next view and the logic that detects missing connections. Inspect how the output-connections list is maintained when a view is removed from the DOM. Done means a missing connection no longer causes an error and the list is repaired.

Written by the indexing model from the issue text.