I had to make a call today and I'm wondering how this scenario should've gone down
The map was a U-shaped hallway; the party was on the lower left of the U, with the enemies on the upper right. The wizard has an owl familiar who could see an enemy caster, with the wizard seeing through the familiar's eyes, and the wizard was further back.
The enemy caster cast a fireball.
The player claims that since he was looking through the owl's eyes from his turn, he should technically have line of sight for a counterspell.
Could counterspell be cast in this case, even though there was a wall between him and the caster, and he was physically not able to cast towards the enemy caster?
Was I wrong in said judgement?