How would Darth Vader feel if Obi Wan Died?

Let's say Hypothetically Obi Wan Kenobi were to die before he and Darth Vader faced each other on The Death Star. And I mean like he either died naturally or someone else who wasn't Vader killed him.

How would Darth Vader feel?

Would he be happy that his greatest enemy is finally dead

Or

Would he be angry because he wasn't the one who killed Kenobi?