Wrong values in subfields when value is switched too quickly

Soemone reported a very specific issue on one of my wikis.

You can test that here: https://archi-mediawiki.netlib.re/Sp%C3%A9cial:RunQuery/Recherche_avanc%C3%A9e?uselang=fr

1. Select France in the Pays field.
2. With the keyboard, use the tab key to select the Ville field.
3. Quickly type str on your keyboard.

What happens then is that Strasbourg is selected but the Sous-quartier and Rue fields are populated with values from Stosswihr (the value before Strasbourg in the Ville list).
This is probably some kind of race condition because the queries are asynchronous.

I had a hard time reproducing on sandbox because you don't have so many values there, but I think I found a similar issue here: https://sandbox.semantic-mediawiki.org/wiki/Sp%C3%A9cial:RunQuery/Test_keyboard

1. With the keyboard, use the tab key to select the first field.
2. Quickly press down then up on your keyboard.

The second field should be empty but it is populated with values from Europe. (Probably because the query for Europe ends after the query for null.)

Reproduce the race condition at the linked ArchiMediaWiki and sandbox pages using the keyboard steps, then trace the asynchronous queries that populate the dependent fields. Done means rapid changes leave the selected value and its dependent fields consistent, including leaving the second field empty when the final selection is null.