Cancel dragging on error

[nikku]

Is your feature request related to a problem? Please describe.

We see times and times again dragging causing massive issue spikes when errors happen (camunda/camunda-modeler#3517). Unfortunately the sheer load of errors prevents us from root causing, and also fills up our error logs.

Describe the solution you'd like

A solution proposed in camunda/camunda-modeler#3517 (comment) is to cancel dragging on error, and this way prevent the flood of issues + clearly indicate the state in which "things broke". Users may still end up in a broken editor state, but at least there is reasonable chance to fix things.

Describe alternatives you've considered

Have a code base with 0 bugs. 🙈

Additional context

Came up again today morning, massive single user spike on demo.bpmn.io.