fix: avoid exit code 1 when output-file is not set

[[ -n "" ]] && ... short-circuits with exit code 1, which the shell
interprets as a failure under set -e. Use an if block so the script
always exits with commit-guard's own exit code.

Signed-off-by: Nerijus Bendžiūnas <nerijus.bendziunas@gmail.com>

Author: benner

action.yml

@@ -97,5 +97,7 @@ runs:
         [[ -n "$CG_REQUIRE_TRAILER" ]] && ARGS+=(--require-trailer "$CG_REQUIRE_TRAILER")
         [[ -n "$CG_OUTPUT_FILE" ]] && ARGS+=(--output-file "$CG_OUTPUT_FILE")
         commit-guard "${ARGS[@]}"
-        [[ -n "$CG_OUTPUT_FILE" ]] && echo "output-file=$CG_OUTPUT_FILE" >> "$GITHUB_OUTPUT"
+        if [[ -n "$CG_OUTPUT_FILE" ]]; then
+          echo "output-file=$CG_OUTPUT_FILE" >> "$GITHUB_OUTPUT"
+        fi
       shell: bash