Stack overflow when recursively assigning something with iterable values

[wader]

$ jq -cn '1 | .. = [.]'
[1]

$ cargo run -- -cn '1 | .. = [.]'
thread 'main' has overflowed its stack
fatal runtime error: stack overflow

$ cargo run -- -n '1 | .. = [2]'
thread 'main' has overflowed its stack
fatal runtime error: stack overflow

$ cargo run -- -n '1 | .. = []'
[]

[01mf02]

@itchyny has already brought this up in #139.

TL;DR: The update behaviour for .. can yield unexpected results for both jq and jaq (they're just more visible in jaq).
Instead of .. |= f, I recommend defining def recurse_up: (.[]? | recurse_up), .; and using recurse_up |= f instead.