better error message

build.sh

@@ -4,8 +4,14 @@ set -e
 set -o pipefail
 
 # Check if all required environment variables are set
-if [ -z "$HF_TOKEN" ] || [ -z "$HF_SPACE_NAME" ] || [ -z "$BUILD_COMMAND" ] || [ -z "$OUTPUT_PATH" ]; then
-    echo "Missing required environment variables"
+missing_vars=()
+[ -z "$HF_TOKEN" ] && missing_vars+=("HF_TOKEN")
+[ -z "$HF_SPACE_NAME" ] && missing_vars+=("HF_SPACE_NAME")
+[ -z "$BUILD_COMMAND" ] && missing_vars+=("BUILD_COMMAND")
+[ -z "$OUTPUT_PATH" ] && missing_vars+=("OUTPUT_PATH")
+
+if [ ${#missing_vars[@]} -ne 0 ]; then
+    echo "Missing required environment variables: ${missing_vars[*]}"
     exit 1
 fi