enum
BadMnemonicReason
Possible reason why a Mnemonic failed validation.
The mnemonic did not contain exactly 24 words.
The checksum encoded in the mnemonic did not match the checksum we just calculated for that mnemonic.
24-word mnemonics have an 8-bit checksum that is appended to the 32 bytes of source entropy after being calculated from it, before being encoded into words.
This could happen if two or more of the words were entered out of the original order or replaced with another from the standard word list (as this is only returned if all the words exist in the word list).
The given mnemonic doesn't contain 22 words required to be a legacy mnemonic, or the words are not in the legacy list.
The mnemonic contained words which were not found in the BIP-39 standard English word list.