The net is a ranged thrown weapon that restrains an enemy that's struck by it, but deals no damage. To avoid the limitation that you don't get extra attacks when throwing a net with an attack action, one option is to use the Battlemaster maneuver "Quick Toss" from Tasha's Cauldron of Everything. Quick Toss allows you to draw and throw a single thrown weapon as a bonus action, adding your superiority die to the damage (and thus leaving your action free to make normal weapon attacks against the restrained target).
Quick Toss says:
If you hit, add the superiority die to the weapon's damage roll.
The net's listed damage is "—". Would I treat that as a roll of zero, roll my superiority die, and deal just the single die of damage; or does "—" mean no damage roll happens and consequently there's nothing to add damage to?