"Doesn't warn about line 2, did I misunderstand yo...

# announcements

[okkero]

"Doesn't warn about line 2, did I misunderstand you?"
This is because line 2 can succeed. If a is null. What @Andreas Sinz said holds true if a is of type String, which he did specify. In your example a is of type String?. If you change the type of a to String you will get the same warning for line 2.