quiet — quiet "missing" errors
quiet(val: any) -> any
The quiet function returns its argument val unless val is
error("missing"), in which case it returns error("quiet").
Various operators and functions treat quiet errors differently than
missing errors, in particular, dropping them instead of propagating them.
Quiet errors are ignored by operators cut, summarize, and yield.
Yield processes a quiet error and thus no output:
echo 'error("missing")' | super -z -c 'yield quiet(this)' -
=>
Without quiet, yield produces the missing error:
echo 'error("missing")' | super -z -c 'yield this' -
=>
error("missing")
The cut operator drops quiet errors but retains missing errors:
echo '{a:1}' | super -z -c 'cut b:=x+1,c:=quiet(x+1),d:=quiet(a+1)' -
=>
{b:error("missing"),d:2}