Why does the friar get so mad Romeo when Romeo complains of being banished? What are the "blessings" for which Romeo should be "happy"?

Romeo isn't being killed like the Prince first threatened, instead he's banished.

Tybalt was going to kill him but died instead.

Juliet is alive.

"And thou dismember'd with thine own defence.

What, rouse thee, man! thy Juliet is alive,

For whose dear sake thou wast but lately dead;

There art thou happy: Tybalt would kill thee,

But thou slew'st Tybalt; there are thou happy too:

The law that threaten'd death becomes thy friend

And turns it to exile; there art thou happy:

A pack of blessings lights up upon thy back..."