I am seeing several random tests fail for unknown reasons. The following two tests expected that the word would be found, but I can't tell why that would be the case:

['T', 'T', 'M', 'D', 'A']
['G', 'Y', 'I', 'N', 'N']
['P', 'A', 'L', 'C', 'E']
['I', 'A', 'U', 'L', 'G']
['A', 'M', 'I', 'N', 'A']

AMINLGIA

[['T', 'T', 'M', 'D', 'A'],
['G', 'Y', 'I', 'N', 'N'],
['P', 'A', 'L', 'C', 'E'],
['I', 'A', 'U', 'L', 'G'],
['A', 'M', 'I', 'N', 'A']]
word is Z

(very confusing - no Z on the board)