Assertion failure with --slurp enabled

[vaughan0]

I accidentally discovered an assertion failure when running jq with the following input:

$ echo -e '{ "foo": 42\n}' | jq --slurp .
jq: jv.c:280: jv_array_length: Assertion `jv_get_kind(j) == JV_KIND_ARRAY' failed.
Aborted

[stedolan]

This was a silly bug in the 'slurp' logic, which was roughly "create a new array if it's the first thing, append to the existing array if it's any later thing".

"thing" should mean "JSON value", but it was implemented as "line of input text".