formr does not accept dash (-) in some choice columns

[dgromer]

I aim to create a questionnaire with the following choice columns: "anchor low", "", "anchor middle", "", "anchor high", i.e., having empty labels for the second and fourth choice.
If I use a whitespace character, it seems to be ignored and I only get choices 1, 3, and 5. So I tried to use a dash (-) as the label and this did work in column choice2, but not in column choice4. Once I add dashes to the choice4 column, re-uploading the spreadsheet gives me an

500

Fatal Error

A fatal error occured and your request could not be completed. Contact site admins with these details
Error [1] in application/Model/Item/Item.php line 315
HUNGOVER-WARTHOG-7183

Having the dashes only in the choice2 column works, but then formr only shows colums 1, 2, 3, and 5.

I attach both a working spreadsheet (dash_test.xlsx) and one that throws an error (dash_test_error.xlsx)

dash_test_error.xlsx
dash_test.xlsx

Am I missing anything here or is there another way to solve this issue?

[dgromer]

After searching the Google group again, I found that this was already discussed and a solution has been proposed: https://groups.google.com/g/formr/c/ukw90XEfcpE/m/Ww3zsfeoAAAJ?pli=1

Edit: And a solution for more than two empty labels: https://groups.google.com/g/formr/c/U-yq-7PWW64/m/RKyr5QJaAAAJ

Would it still be possible to throw a somewhat more informative error message?