When does Phalcon\Mvc\Model::save() return false?

[s-ohnishi]

The documentation says:

Inserts or updates a model instance. Returning true on success or false otherwise.
...
$result = $invoice->save();

However, PDO's error reporting mode defaults to PDO::ERRMODE_EXCEPTION since PHP8, and I don't think Phalcon can be set otherwise.
Then, won't an exception be thrown when saving fails?
Can anyone give me a concrete example?
If an exception is thrown, isn't it pointless to receive the return value like this?

Similarly, what about create()?

Inserts a model in the database.If the record exists in the database, create() will throw an exception. It will return true on success, false otherwise.
...
$result = $invoice->create();

It is specified that an exception may be thrown (when the unique constraint is violated?), but what if false is returned without an exception being thrown?

Also, what about update()?