Segfault on reading of list containing unquoted strings

[miker2]

Attempting to read a config that looks like this:

struct foo {
  bar = [this, is, broken]

  struct baz {
    bad_key = broken
  }
}

Results in a segfault. This is clearly a malformed config, but a more useful error message could be produced.

[jayv]

This was very likely fixed as part of #127 which fixes a segfault when logging empty lists.