FullChainFile chain may be an empty list

[dracos]

simp_le/simp_le.py

Line 709 in 8f258bc

if data.chain is None:

tests if data.chain is None, but its parent's load_from_content means that if e.g. the file exists but is empty or corrupt, it will be an empty list. I think the check should also check for the empty list as well as None.

$ touch foo.pem
$ python
>>> import simp_le
>>> simp_le.FullChainFile(path="foo.pem").load()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "simp_le.py", line 713, in load
    cert, chain = data.chain[0], data.chain[1:]
IndexError: list index out of range