For words that only have three letters, there isn't a 4th letter. By way of example with the word “incorporate”, there are no a lot more letters Later on and thus needs to be the word "incorporate". The word “addict” is in the BIP39 wordlist however, you might have made https://bookmarkvids.com/story20150496/invalid-bip39-phrase-things-to-know-before-you-buy