[FIX] web: crash in editable lists with date field

Assume an editable list view with a date(time) widget, click to
edit a line, focus the date field (the datepicker opens), press
ESC: there is a crash in the lib, and the datepicker remains open
forever.

This fix is twofold:
 - we added a check in the lib to prevent it from crashing (it is
 easily reproducible: it crashes when an opened datepicker is
 removed from the DOM).
 - we added an event handler of ESC keydown event to hide the
 datepicker before the field is removed from the DOM.