when write bucket failed, why return nil instead of err?

[czh0526]

the error is in file waddrmgr/db.go at line 1216

func putAddrAccountIndex(...) error {
....

    // Write account keyed by address hash
err = bucket.Put(addrHash, uint32ToBytes(account))
if err != nil {
	return nil
}

     .....

}

[yyforyongyu]

think it's a mistake we should fix🤔