load_helps crashes on an empty help keyword that ROM's loader accepts

[ctoth]

AreaFile.load_helps indexes the keyword before checking it:

https://github.com/ctoth/area_reader/blob/3297b88/area_reader/__init__.py#L380-L389

def load_helps(self):
    while True:
        level = self.read_number()
        keyword = self.read_string()
        if keyword[0] == '$':
            break

A help entry with an empty keyword (5 ~) makes keyword[0] raise IndexError, which the section wrapper re-raises as a generic ParseError. Reproduced:

#HELPS
5 ~
some text~
0 $~

ParseError: ...\h.are line 8 col 3 in section helps: Error reading section 'helps'
(underlying: IndexError from keyword[0])

ROM's C loader accepts this file: fread_string returns an empty string and keyword[0] is '\0', which is not '$', so the help is stored. So this is a file the reference engine loads and area_reader rejects.

Fix: if keyword.startswith('$'):.