Insert query fails silently after upgrading to 4.6

[lsdch]

• EdgeDB Version: 4.6+0632dff
• EdgeDB CLI Version: 4.1.0+03ae624
• OS Version: Linux Mint 21.3

Steps to Reproduce:

1. Migrate the provided schema on an EdgeDB 4.6 instance
2. Run query:

   select (insert people::Person {
   first_name:= "Test",
   last_name:= "TEST"
   }) { * }
   # Returns an empty set

   Running only the insert statement also return an empty set.
   Checking the database content confirms that the item was not inserted. Insertion of other object types seems to work, although I only tested a few of them.

Everything works as expected on v4.5.

Schema:

• Schema definition files: https://gist.github.com/lsdch/22ea6f875e7df4481e73da26dd0ca891
• Migration file: https://gist.github.com/lsdch/cca2800c7ab63f431d1fe3ab2d818298

[msullivan]

Thanks for the report!

This issue is a knock-on effect of https://github.com/edgedb/edgedb/issues/7061.

Because the cardinality of the current_user global gets inferred incorrectly in queries, we perform some optimizations that are unsound when dealing with something of optional cardinality.

This will be fixed in 4.7 by reverting #6613 and in 5.x by https://github.com/edgedb/edgedb/pull/7062