Prevent crash in EncryptInPlace when the encrypter is missing
Prevent crash in EncryptInPlace when the encrypter is missing

I'm currently investigating exactly what can cause this crash but I believe this could happen in production so I'd rather put this fix in now as a safety measure and build a repro test shortly after.

gfe-relnote: n/a, replace a crash with a QUIC_BUG
PiperOrigin-RevId: 243903209
Change-Id: I14403f3ed648c56f4d197b8d36e180639237dacb

google/quiche,google/quiche,google/quiche,google/quiche