I was getting duplicated parens when inserting fractions and tracked down the issue to smartparens-mode.

It seems like laas tries to handle this through the function laas--shut-up-smartparens, so I was surprised that it wasn't working.

However, when deciding whether it needs to manipulate the post-self-insert-hook, it checks the default value of post-self-insert-hook rather than the present (potentially local) value. As far as I can tell, smartparens-mode modifies this hook locally and does not alter the default value. As a result, laas--shut-up-smartparens erroneously believes that it does not need to shut up smartparens-mode even though it should.