MaxMilton/ekscss-repl

diff --git a/lib/nodes/node/Node.js b/lib/nodes/node/Node.js
index ab306f8b520362c6c54571b7ee360fe6b0c58ba8..a45c634b54221c13e84adcc51933bb1bfd4177ed 100644
--- a/lib/nodes/node/Node.js
+++ b/lib/nodes/node/Node.js
@@ -436,7 +436,7 @@ class Node extends EventTarget {
         if (this[PropertySymbol.isConnected] !== isConnected) {
             this[PropertySymbol.isConnected] = isConnected;
             if (!isConnected) {
-                if (this[PropertySymbol.ownerDocument][PropertySymbol.activeElement] === this) {
+                if (this[PropertySymbol.ownerDocument]?.[PropertySymbol.activeElement] === this) {
                     this[PropertySymbol.ownerDocument][PropertySymbol.activeElement] = null;
                 }
             }