Render MessageReasoning only if text is present

Updated the condition to render the MessageReasoning component only when the part type is 'reasoning' and part.text exists. This prevents rendering empty reasoning components.

Author: haydenbleasel

components/message.tsx

@@ -103,7 +103,7 @@ const PurePreviewMessage = ({
               const { type } = part;
               const key = `message-${message.id}-part-${index}`;
 
-              if (type === 'reasoning') {
+              if (type === 'reasoning' && part.text) {
                 return (
                   <MessageReasoning
                     key={key}