Promote warning to exception in ext/sysvsem

[kocsismate]

No description provided.

[nikic]

I'm unsure about this one.

[kocsismate]

@nikic What's the problem with this one? Isn't it somewhat similar to the cases when we throw if a connection is not open? Or there are use-cases when people (have to) call sem_release() not knowing if the semaphore has already been acquired?

[nikic]

This seems a bit different. It's not about being not open / uninitialized, but about performing an unlock without a lock. Best analogy to other extensions we have would probably be to commit/rollback without starting a transaction.

Then again, unlock without lock does seem like a clear programming error...

[kocsismate]

In case of doubt, then the best we can do is to close the PR :) It not a big waste.