- go to a File page that has a statement with qualifiers (e.g. https://commons.wikimedia.beta.wmflabs.org/wiki/File:Photo_on_20-06-2019_at_12.36.jpg)
- click 'edit' on structured data panel showing the statement with its qualifiers
- change one of the qualifiers so that its property has a different type (e.g. if the property has type entity change it to one with type quantity, or vice versa) - but don't change the value
- click 'submit'
- verify that the qualifier has been deleted (because it had no value)
- verify that the statement panel can again be edited