[mapaba79]

Problem

to_entropy() looks up each word's index with list.index():

ndx = self.wordlist.index(self.normalize_string(word))
if ndx < 0:
    raise LookupError('Unable to find "%s" in word list.' % word)

list.index() never returns a negative value — when the element is
not found, it raises ValueError directly instead of returning -1.
As a result, the if ndx < 0 branch is unreachable: it can never be
true, because if the word isn't in the wordlist the exception is
already raised two lines earlier, before the check even runs.

Impact

When an invalid/misspelled word is passed to to_entropy(), callers
get a raw ValueError with Python's generic list-lookup message
(e.g. 'notaword' is not in list) instead of the intended,
descriptive LookupError (Unable to find "notaword" in word list.). This is misleading for end users debugging a bad mnemonic,
and breaks any caller that specifically catches LookupError
(matching how the rest of this library reports lookup failures)
without also catching ValueError.

Reproduction

from mnemonic import Mnemonic
m = Mnemonic("english")
m.to_entropy("abandon " * 11 + "notaword")
# ValueError: 'notaword' is not in list

Fix

Wrap the .index() call in a try/except ValueError and raise the
intended LookupError from there, instead of checking a condition
that can never be true:

try:
    ndx = self.wordlist.index(self.normalize_string(word))
except ValueError:
    raise LookupError('Unable to find "%s" in word list.' % word)

Testing

• Reproduced the original issue against a clean checkout: confirmed
  a raw ValueError was raised instead of LookupError.
• Applied the fix and re-ran the same reproduction: confirmed
  LookupError: Unable to find "notaword" in word list. is now
  raised as intended.
• Ran the full existing test suite (pytest tests/) before and
  after the change: all 7 tests pass in both cases, confirming no
  regression to existing checksum/entropy behavior.

This is a pure error-handling fix; the entropy/checksum computation
logic is unchanged.

[fametrano]

I'd keep ValueError here and leave the word itself out of the message. to_entropy already raises ValueError for a wrong word count and a bad checksum, and LookupError is not a subclass of it, so code that catches ValueError today would miss this error. A misspelled word is usually one or two letters from a word of the mnemonic and exception messages end up in logs, so the position is safer, for example word 12 is not in the word list.

[fametrano]

This keeps ValueError and gives the position instead of the word. Raising outside the except block also keeps the original 'abuot' is not in list out of the exception and its traceback.

Suggested change

	try:
	ndx = self.wordlist.index(self.normalize_string(word))
	except ValueError:
	raise LookupError('Unable to find "%s" in word list.' % word)
	try:
	ndx = self.wordlist.index(self.normalize_string(word))
	except ValueError:
	ndx = -1
	if ndx < 0:
	raise ValueError("Word %d is not in the word list." % (wordindex + 1))