One can use read and redirection if the files are line delimited. Preferring while/read to expansion makes for more robust scripts.

gistfile1.sh

#!/bin/bash
set -o errexit -o pipefail -o nounset

cat_bundle () {
    local file="$1"
    echo ""
    echo ""
    echo "; ----------------------------------------------------------------------"
    echo "; $(basename $file)"
    echo "; ----------------------------------------------------------------------"
    echo ""
    cat "$file"
}


echo
echo "SUMMARY"
echo "-------"
T="$(mktemp -d -t aura-test.XXXX)"
mkdir -p dist
rm -f dist/tmp
ln -s "$T" dist/tmp
for i in output/batch/*.bundles.output; do
    BUNDLE="$(basename "$i" .output)"
    mkdir "$T/$BUNDLE"
    grep -rl "Status code: 400" "$i" | sed -e "s!$i/!!" > "$T/$BUNDLE"/awful-input
    grep -rl "NO RESULTS" "$i"       | sed -e "s!$i/!!" > "$T/$BUNDLE"/no-results

    NUM_BAD="$(wc -l "$T/$BUNDLE"/no-results | awk '{print $1}')"
    NUM_AWFUL="$(wc -l "$T/$BUNDLE"/awful-input | awk '{print $1}')"
    echo "$BUNDLE     $NUM_BAD bad    $NUM_AWFUL awful"

    TB="$T/$(basename $BUNDLE .bundles)"
    if [[ $NUM_AWFUL -gt 0 ]]; then
        while read -r bad; do
          cat_bundle output/batch/"$BUNDLE".input/"$bad"
        done < <(cat "$T/$BUNDLE"/awful-input)
    fi >> "$TB".awful-input.bundles
    if [[ $NUM_BAD -gt 0 ]]; then
        while read -r bad; do
          cat_bundle output/batch/"$BUNDLE".input/"$bad"
        done < <(cat "$T/$BUNDLE"/no-results)
    fi >> "$TB".no-results.bundles
done | column -t