When trying to create a procedure, either through the DB Explorer or DB Navigator, an 'Ora-00942: table or view does not exist' error is received.
If the user has Select_Catalog_Role granted to them, SQL Navigator runs a different query than normal, which queries from sys.user$. The Select_Catalog_Role does not grant access to sys.user$ and the user does not have access to it, so the user receives an 'Ora-00942: table or view does not exist' error.
Grant SELECT privilege to sys.user$.
Waiting for fix to be released in a future version of SQL Navigator.