Do black puddings corrode slashing weapons

Question

Black puddings are immune to slashing damage, and the Corrosive Form trait states:

... Any nonmagical weapon made of metal or wood that hits the pudding corrodes. After dealing damage, the weapon takes a permanent and cumulative-1 penalty to damage rolls. ...

The bit that confuses me is "after dealing damage". If the pudding is immune to slashing damage, then slashing weapons will never deal damage, and thus should not take the -1 penalty. However, that seems to contradict the previous statement, that anything that hits will corrode.

Answer 1

There is much debate on if dealing 0 damage counts as dealing damage.

This question has lots of differing opinions: Does something count as "dealing damage" if its damage is reduced to zero?

There is a clear rule intent here that should be followed: slashing weapons still degrade.

The rule in question is:

After dealing damage, the weapon takes a permanent and cumulative-1 penalty to damage rolls.

It seems clear to me that "after dealing damage" is used to indicate that the damage penalty for the weapon is not accounted for on this attack, not that slashing weapons are mysteriously impervious to oozes. It seems abundantly clear that the intent is that the slashing weapons also degrade, even if they cannot damage the pudding. So regardless of what the RAW is, slashing weapons obviously should still be susceptible - and this makes perfect sense narratively. The slashing weapon harmlessly passes through the slime, * but it's still getting all slimy*. It should still corrode the slashing weapon.