fix: report filename if template file is invalid A file name like .#issue.search.html causes a crash because _find returns None not a tuple and unpacking fails. Trap the TypeError and raise ValueError with message that includes the basename of the file.

try:
    # Python 3+
    from ssl import SSLError
except (ImportError, AttributeError):
    # Python 2.5-2.7
    from socket import sslerror as SSLError  # noqa: F401