As long as the first spell goes off it should.

Cast spell
use trinket - can't
stop spell

or

cast spell - can't/feared
use trinket - removes fear
stop spell - stop's nothing

But if you get:

Cast spell - can't
use trinket - wasted
stop spell

Then it's a problem. This would happen if you are moving and thus can't cast a spell. If you are already casting a spell it would cancel that spell.