If you, too, have had a numpty moment....
What to do?
1. Don't panic.
2. Don't leave it or run the machine, either. The detergent can knacker the internal water softening system mechanism, expensive to replace & repair!
3. Do spoon out or otherwise remove the powder. Siphon off the liquid (the powder & liquid can still be reused, by the way, no need to bin).
4. Siphon the compartment empty if you can't empty it any other way. Flush the compartment out thoroughly, and siphon it empty again, too.
5. After 2-3 flushing & siphoning sessions, refill the compartment with SALT and you should be able to use the machine as normal.
6. That's what I did and so far so good! Machine appears to be normal, phew.
Just to rub salt in the wounds, the lid on our salt compartment had "salt" written on it in lots of languages!
Sal, Tuz, So, Salz, Salt, Zout, Suola, A?ati, Sel, Sale.