fix: Handle empty message content for suggestion threads

application/src/main/java/org/togetherjava/tjbot/features/basic/SuggestionsUpDownVoter.java

@@ -23,7 +23,6 @@
  */
 public final class SuggestionsUpDownVoter extends MessageReceiverAdapter {
     private static final Logger logger = LoggerFactory.getLogger(SuggestionsUpDownVoter.class);
-    private static final int TITLE_MAX_LENGTH = 60;
     private static final Emoji FALLBACK_UP_VOTE = Emoji.fromUnicode("👍");
     private static final Emoji FALLBACK_DOWN_VOTE = Emoji.fromUnicode("👎");
 
@@ -55,19 +54,10 @@ public void onMessageReceived(MessageReceivedEvent event) {
     }
 
     private static void createThread(Message message) {
-        String title = message.getContentRaw();
+        ThreadTitle threadTitle = ThreadTitle.withFallback(message.getContentRaw(),
+                message.getAuthor().getName() + "'s suggestions");
 
-        if (title.length() >= TITLE_MAX_LENGTH) {
-            int lastWordEnd = title.lastIndexOf(' ', TITLE_MAX_LENGTH);
-
-            if (lastWordEnd == -1) {
-                lastWordEnd = TITLE_MAX_LENGTH;
-            }
-
-            title = title.substring(0, lastWordEnd);
-        }
-
-        message.createThreadChannel(title).queue();
+        message.createThreadChannel(threadTitle.value()).queue();
     }
 
     private static void reactWith(String emojiName, Emoji fallbackEmoji, Guild guild,

application/src/main/java/org/togetherjava/tjbot/features/basic/ThreadTitle.java

@@ -0,0 +1,44 @@
+package org.togetherjava.tjbot.features.basic;
+
+/**
+ * Represents a thread title, enforcing a maximum length of 60 characters. If an initial title
+ * exceeds this limit, it's truncated at the last word boundary before or at the 60-character mark
+ * to prevent cutting words mid-sentence. If no space is found, it truncates at 60 characters.
+ * Provides a static factory method `withFallback` to create a ThreadTitle, using a fallback title
+ * if the primary title is empty.
+ */
+public record ThreadTitle(String value) {
+
+    private static final int TITLE_MAX_LENGTH = 60;
+
+    public ThreadTitle(String value) {
+        String threadTitle;
+        if (value.length() >= TITLE_MAX_LENGTH) {
+            int lastWordEnd = value.lastIndexOf(' ', TITLE_MAX_LENGTH);
+
+            if (lastWordEnd == -1) {
+                lastWordEnd = TITLE_MAX_LENGTH;
+            }
+
+            threadTitle = value.substring(0, lastWordEnd);
+        } else {
+            threadTitle = value;
+        }
+
+        this.value = threadTitle;
+    }
+
+    public static ThreadTitle withFallback(String primary, String fallback) {
+        if (!primary.isEmpty()) {
+            return new ThreadTitle(primary);
+        } else {
+            return new ThreadTitle(fallback);
+        }
+    }
+
+    @Override
+    public String toString() {
+        return value;
+    }
+
+}