diff --git a/tools/basic.js b/tools/basic.js
index 2c086b1d..8fa21fa9 100644
--- a/tools/basic.js
+++ b/tools/basic.js
@@ -1,9 +1,13 @@
 function MouseOverBigButton(source) {
-  source.firstChild.style.visibility = "visible";
+	if (source?.firstChild?.style) {
+		source.firstChild.style.visibility = "visible";
+	}
 }
 function MouseOutBigButton(source) {
-  source.firstChild.style.visibility = "hidden";
+	if (source?.firstChild?.style) {
+		source.firstChild.style.visibility = "hidden";
+	}
 }
 function BigButtonAction(path) {
   window.location = path;
-}
\ No newline at end of file
+}