git_auto_update: Added check for if no release tag can't be found

roles/git_auto_update/templates/update.sh

@@ -25,7 +25,11 @@ git remote set-url origin "$REPO";
 
 git fetch --recurse-submodules --tags > /dev/null;
 TAG=$(git tag --list | grep "^$PREFIX" | sort -r | head -n 1);
-if [ -z "$GPG_FINGERPRINT" ] || (git verify-tag --raw "$TAG" 2>&1 | grep --fixed-strings " VALIDSIG $GPG_FINGERPRINT ") > /dev/null; then
+
+if [ -z "$TAG" ]; then
+  error "No release tag found";
+  exit 1;
+elif [ -z "$GPG_FINGERPRINT" ] || (git verify-tag --raw "$TAG" 2>&1 | grep --fixed-strings " VALIDSIG $GPG_FINGERPRINT ") > /dev/null; then
   git reset --quiet --hard --recurse-submodules;
   git checkout --quiet --recurse-submodules "$TAG";
   chown --recursive "$DEST_USER:$DEST_GROUP" .;