diff --git a/app/util.js b/app/util.js
index d4379a1..5df8261 100644
--- a/app/util.js
+++ b/app/util.js
@@ -1,9 +1,11 @@
-halfmoon.showModal = id => {
-    const t = document.getElementById(id)
-    t && t.classList.add("show")
-}
-halfmoon.hideModal = id => {
-    const t = document.getElementById(id)
-    t && t.classList.remove("show")
+if ((typeof halfmoon === "object" || typeof halfmoon === 'function') && (halfmoon !== null)) {
+    halfmoon.showModal = id => {
+        const t = document.getElementById(id)
+        t && t.classList.add("show")
+    }
+    halfmoon.hideModal = id => {
+        const t = document.getElementById(id)
+        t && t.classList.remove("show")
+    }
 }