Getting token() function first tries to find a schema for underlying
table and continues with nullptr if there's no one. Later, when creating
token_fct, the schema is passed as is and referenced. If it's null crash
happens.
It used to throw before 5983e9e7b2 (cql3: test_assignment: pass optional
schema everywhere) on missing schema, but this commit changed the way
schema is looked up, so nullptr is now possible.
fixes: #18637
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Closesscylladb/scylladb#18639