creating new account with same username/eid does not return error in HSQLDB

If running on HSQLDB and you create a new user with a username/eid that already exists, you do not receive any error onscreen so you don't know what happened, but you get an SQLException in the logs.

.....
Caused by: java.sql.SQLException: Violation of unique index AK_SAKAI_USER_ID_MAP_EID: duplicate value(s) for column(s) EID in statement [insert into SAKAI_USER_ID_MAP (USER_ID, EID) values (?,?)]
at org.hsqldb.jdbc.Util.throwError(Unknown Source)

if running on MySQL, the exception is caught as expected and you receive the "Alert: The user id is already in use"

This is because UsersAction.java only catches specific Exceptions, which must not be being thrown properly in HSQLDB

try
{
// add the user in one step so that all you need is add not update permission
// (the added might be "anon", and anon has add but not update permission)
User newUser = UserDirectoryService.addUser(id, eid, firstName, lastName, email, pw, type, null);

// put the user in the state
state.setAttribute("newuser", newUser);
}
catch (UserAlreadyDefinedException e)
{
addAlert(state, rb.getString("useact.theuseid1"));
return false;
}
catch (UserIdInvalidException e)
{
addAlert(state, rb.getString("useact.theuseid2"));
return false;
}
catch (UserPermissionException e)
{
addAlert(state, rb.getString("useact.youdonot3"));
return false;
}

Perhaps a generic catch at the end to catch any other exceptions or modify UserDirectoryService.addUser() so it throws the correct exception in HSQLDB