Add error checks to key.{En,De}cryptBytes(nil)
Add error checks to key.{En,De}cryptBytes(nil)

in TestTwofishEncryption

ericflo/Sia,ChrisSchinnerl/Sia,Mingling94/Sia,mharkus/Sia,ChrisSchinnerl/Sia,mharkus/Sia,MrStrong/Sia,NebulousLabs/Sia,rivine/rivine,mnsl/Sia,ericflo/Sia,rivine/rivine,mtlynch/Sia,NebulousLabs/Sia,MrStrong/Sia,mnsl/Sia,johnathanhowell/Sia,mtlynch/Sia