For words that have only three letters, there is no 4th letter. Such as with the word “insert”, there are no more letters afterwards and so need to be the word "add". The word “addict” is from the BIP39 wordlist however , you might have utilised “addi” for “addict”. How https://nybookmark.com/story20436650/an-unbiased-view-of-bip39-seed-phrase-github