Strange error message when using unknown JSON function with default database

MariaDB [(none)]> select json_unique("abcd");

ERROR 1305 (42000): FUNCTION json_unique does not exist

MariaDB [(none)]> use test;

Reading table information for completion of table and column names

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Database changed

MariaDB [test]> select json_unique("abcd");

ERROR 1728 (HY000): Cannot load from mysql.proc. The table is probably corrupted