Thanks @aaron for the detail!
Indeed, the words list defined in the incognito repository here is invalid .
It produces this kind of words (with spaces):
'abandon', ' ability', ' able', ' about', ' above',
' absent', ' absorb', ' abstract', ' absurd', ' abuse',
' access', ' accident', ' account', ' accuse', ' achieve',
' acid', ' acoustic', ' acquire', ' across', ' act',
' action', ' actor', ' actress', ' actual', ' adapt',
' add', ' addict', ' address', ' adjust', ' admit',
' adult', ' advance', ' advice', ' aerobic', ' affair',
' afford', ' afraid', ' again', ' age', ' agent',
' agree', ' ahead', ' aim', ' air', ' airport',
' aisle', ' alarm', ' album', ' alcohol', ' alert',
' alien', ' all', ' alley', ' allow', ' almost',
' alone', ' alpha', ' already', ' also', ' alter',
' always', ' amateur', ' amazing', ' among', ' amount',
' amused', ' analyst', ' anchor', ' ancient', ' anger',
' angle', ' angry', ' animal', ' ankle', ' announce',
' annual', ' another', ' answer', ' antenna', ' antique',
' anxiety', ' any', ' apart', ' apology', ' appear',
' apple', ' approve', ' april', ' arch', ' arctic',
' area', ' arena', ' argue', ' arm', ' armed',
' armor', ' army', ' around', ' arrange', ' arrest',
' typical' ...