Stop being able to crash NeoChat by pressing a button repeatedly

If you spam click the "Close link preview" button, it's possible to
crash NeoChat. This is because the index check is wrong for the array
size.

It's possible to even do this due to a bug causing the removal to be
reflected visually too slowly, that's fixed in the next commit.

src/models/messagecontentmodel.cpp

@@ -635,7 +635,7 @@ QList<MessageComponent> MessageContentModel::addLinkPreviews(QList<MessageCompon
 
 void MessageContentModel::closeLinkPreview(int row)
 {
-    if (row < 0 || row > m_components.size()) {
+    if (row < 0 || row >= m_components.size()) {
         qWarning() << "closeLinkPreview() called with row" << row << "which does not exist. m_components.size() =" << m_components.size();
         return;
     }