When the time is manually edited in a datetime field, there is a JS error.

This error is only in the JS console and does not impact the user.

Repro steps :

1. Modify a datetime field in front-edition
2. If there is already a time, erase the last number
3. If not, write the beginning of a time (E.G. "12:")

Boom :

Uncaught TypeError: Cannot read property 'length' of null

Note : this error only appears when the time format is invalid.