Spectating a Lead with F3 Crash

When I tried to spectate a lead knot (With F3 already open), my game crashed. I tried to recreate it, but nothing happened. Then I decided to open up F3 while spectating a lead, and it crashed again.

I don't know what other entities also have the same effect, but I'm sure some do.

Description: Unexpected error

java.lang.NullPointerException: Unexpected error
	at bnw.b(SourceFile:91)
	at bnw.a(SourceFile:55)
	at bnw.a(SourceFile:47)
	at bnm.a(SourceFile:203)
	at cdn.b(SourceFile:993)
	at bmi.ap(SourceFile:886)