Fix shellcheck error in docker-compose-with-error.sh
#!/bin/bash
# shellcheck disable=SC2086
-# You can pass TARGETS to this script to specify
-# which services to run, instead of all of them, which is the default behavior.
-TARGETS="${TARGETS}"
+# This script will honor the TARGETS environment variable to specify
+# which services to run, instead of all of them, which is the default
+# behavior.
+TARGETS="${TARGETS:-}"
set -eu
