diff --git a/client/src/components/ContentBlock.vue b/client/src/components/ContentBlock.vue
index 2af97c27..dfd3b9b1 100644
--- a/client/src/components/ContentBlock.vue
+++ b/client/src/components/ContentBlock.vue
@@ -269,7 +269,7 @@ onUnmounted(() => {
 
   if (element !== null) {
     console.log('unmounting');
-    element.removeEventListener('mouseup', getSelectionHandler);
+    element.removeEventListener('mouseup', getSelectionHandler(element, props.contentBlock));
   }
 });
 
diff --git a/client/src/directives/highlight.ts b/client/src/directives/highlight.ts
index f33f7196..c2c1b918 100644
--- a/client/src/directives/highlight.ts
+++ b/client/src/directives/highlight.ts
@@ -102,13 +102,13 @@ export const getSelectionHandler = (el: HTMLElement, contentBlock: ContentBlockN
         const paragraph = findClosestAncestorWithTag(startContainer, 'p');
         const endAncestor = findClosestAncestorWithTag(endContainer, 'p');
 
-        if (paragraph === endAncestor) {
+        if (paragraph && paragraph === endAncestor) {
           // todo: rename this variable, `parent` is not correct anymore
           const contentComponent = findClosestAncestorWithClass(startContainer, 'content-component');
           if (contentComponent) {
             // our selection is wholly inside the container node, we continue with it
             const position = findPositionInParent(contentComponent);
-            const siblings = Array.from(paragraph.parentElement.children);
+            const siblings = Array.from(paragraph.parentElement?.children || []);
             const positionInTextBlock = siblings.indexOf(paragraph);
 
             const numOfParagraphs = Array.from(contentComponent.children[1].children).filter(