Web UI Bug: No error message when creating a conflicting unique index

How to reproduce

Precondition:

You have a collection in MongDB Atlas that has some date. At least two documents have the same value for a field. (eg. the same “email”)

Use Case
Now try to create a unique index for that “email” field via the web ui. Put in the options field: {unique: true}

Expected behaviour
The creation must fail, because there are conflicting values in the existing documents. Two documents that already have the same value in the “emai” field. (For whatever reasons. They are just there)
=> The UI shouhld show an error

Actual behaviour
The index is not created. But the operation silently fails. No error is shown.