‘Arrant’ not errant’

I was puzzled to see the term “Errant nonsense” headlining Hugh Jaynas’ letter, as well as embedded in the epistle itself. A secondary meaning of the word “errant” means erring or straying; but the primary meaning is wandering in search of adventure, as in the term “knight errant”, meaning a wandering knight.
Given the superabundance of nonsense inundating our world today, I suppose it might be possible to find some of it wandering around in search of adventure.  But I suspect that what Mr Jaynas meant was “arrant nonsense”, which means utter nonsense.
Fastidious blowhards like myself would appreciate it if writers to this august column would make sure they know the meanings of the words they use before setting fingers to keyboard.
Fussily,
Ye Olde Pedant