non-error
unshakable
errorlessly
bugless
nondiagnostically
unflawed
flawless
correction
nonproblem
nonemergency
near thing
compatible
kluge
unassailable
watertight
bulletproof
ironclad
get out of jail free card
utility
immaculately
errorful
unblundered
need-not
inappositely
unsententiously
nonlogarithmically
warts and all
flyspeck
nonchallenge
nonthreat
smooth sailing
incorrupted
impeccable
faultless
immaculate
trouble-free
non-prerequisite
apposite
crutch
nonfailure
unmaliciously
approximator
nonmonotonically
unofficiously
unerringly
accurately
nonmutator
nonviolation
nonexample
clean