bug: "Cube can only have one maintable" despite not having a main table

[CDiGallo]

Describe the bug
I want to create a new cube. I select 3 of 4 possible dimensions. click on new table. Want to make a main table. Get error "you can only have one maintable" instead.

Affected functionalities (all that apply)

• [x ] CSV Mapping
• Transformation
• Publishing
• Other

Relevant links
https://test.cube-creator.lindas.admin.ch/app/cube-projects/cube-project!!bugtestsalkosjdfoajdofkj-9nnxzklnger/csv-mapping/tables/create?source=cube-project!!bugtestsalkosjdfoajdofkj-9nnxzklnger!!csv-mapping!!csv-source!!luftbelastung-entlang-der-a2-und-der-a13-jahresmittelwerte-no-und-no2-full-csv-dw8qqoxa4ld&columns=cube-project!!bugtestsalkosjdfoajdofkj-9nnxzklnger!!csv-mapping!!csv-source!!luftbelastung-entlang-der-a2-und-der-a13-jahresmittelwerte-no-und-no2-full-csv-dw8qqoxa4ld!!column!!zeitliche-referenz-eo80jpgldwd&columns=cube-project!!bugtestsalkosjdfoajdofkj-9nnxzklnger!!csv-mapping!!csv-source!!luftbelastung-entlang-der-a2-und-der-a13-jahresmittelwerte-no-und-no2-full-csv-dw8qqoxa4ld!!column!!luftschadstoff-da18903eoak&columns=cube-project!!bugtestsalkosjdfoajdofkj-9nnxzklnger!!csv-mapping!!csv-source!!luftbelastung-entlang-der-a2-und-der-a13-jahresmittelwerte-no-und-no2-full-csv-dw8qqoxa4ld!!column!!konzentration-g-m-we0wze886m7

To Reproduce
Steps to reproduce the behavior:

1. Go to 'create new table out of the csv (maybe only with not full amount of csv'
2. Click on 'main table'

maybe 3. Scroll down to 'leave the id field empty (so that it auto-generates)

4. See error

Expected behavior
creating main table

Screenshots

[CDiGallo]

additional info:
first, this exists on TEST and INT. secondly. There is a workaround: create cube withouth the "maintable" check mark create table and change it afterwards