Why does this fish while loop terminate after a single iteration? - npm

Question

This is a fish function used to upgrade JavaScript packages for a project. Strangely, it terminates after a single iteration with an exit status of 0. Why?
function yarn-upgrade-all --description "Upgrade JavaScript packages"
yarn outdated | sed '1,/^Package/d;/^Done/d' | awk '{print $1, $4}' | while read -l PACKAGE VERSION
echo
set_color brwhite
echo -n "==>"
set_color yellow
echo -n " "$PACKAGE
set_color brblue
echo -n " "$VERSION
set_color brwhite
echo -n " <=="
set_color normal
echo
echo
yarn upgrade --latest $PACKAGE
and yarn run test
and yarn run build
and git commit -am "Upgrade to "$PACKAGE" "$VERSION
or begin
set_color red
echo "last command exited with status $status" >&2
set_color normal
return 1
end
end
end
On the other hand, this second function, which contains only a stub body, runs through all packages piped into the loop.
function yarn-upgrade-all-debug --description "Upgrade JavaScript packages"
yarn outdated | sed '1,/^Package/d;/^Done/d' | awk '{print $1, $4}' | while read -l PACKAGE VERSION
echo $PACKAGE $VERSION
end
end
fish --version
fish, version 3.0.2

Answer 1

You're running fish 3.0.0, and hitting https://github.com/fish-shell/fish-shell/issues/5513 - return from a while doesn't actually set the status correctly.
However, the return still causes it to terminate the while-loop.
Upgrade to 3.0.2.

Answer 2

The loop terminates after a single iteration because the yarn run invocations in the loop body slurp up the rest of stdin. (Credits to #glenn-jackman.)
A possible workaround is to redirect stdin to /dev/null for these commands:
and yarn run test < /dev/null
and yarn run build < /dev/null
The culprit is run-s from the npm-run-all package, which is invoked by both yarn run commands.
https://github.com/mysticatea/npm-run-all/issues/166