This is an accepted solution.
Hello @rascalroots ,
Seems you repeated the code twice but can't confirm without checking the code.
I suggest install fresh copy of Dawn theme and then check there or get password files from fresh theme.
This error because you changed the code of the layout/password.liquid file.
Please change all code password.liquid file with default code of Dawn, it will work fine.
If my answer can help you solve your issue, please mark it as a solution. Thank you and good luck.