TCA: Fix error not displayed after QR code scanning failure
In such cases, TCA would raise an exception while trying to display the error to the user: "TypeError: 'dict' object is not callable" for "_"
This is a regression introduced in 5.14 by 31e4b9df. One instance of the bug was fixed in 30b6842e, but some others remained, or could start happening whenever we start using "_" to localize strings in the affected code paths.
Closes #19737 (closed)