Index cursors are a special type of cursor that has it's keys at the values of the table. The wiredtiger documentation describes this feature quite well https://source.wiredtiger.com/11.0.0/schema.html#schema_indices.

Currently the standard behaviour of a cursor read, insert type operation is that it checks if the key is set, and returns back an error if the key is not set. There is currently a bug within the index cursors implemenetations where we do not do this check, eventually running into an assert getting hit.

This ticket should delve into the cur_index.c file and look at possible operations that require a key, and add the __cursor_checkkey such that we don't hit the assert. The developer will also need to write a test to make sure this is all correct now.