fix: restore Telegram topic announce delivery (#51688) (thanks @mvanhorn)

When `replyLike.text` or `replyLike.caption` is an unexpected
non-string value (edge case from some Telegram API responses),
the reply body was coerced to "[object Object]" via string
concatenation. Add a `typeof === "string"` guard to gracefully
fall back to empty string, matching the existing pattern used
for `quoteText` in the same function.

Co-authored-by: Penchan <penchan@penchan.co>

extensions/telegram/src/bot/helpers.test.ts

@@ -248,6 +248,25 @@ describe("describeReplyTarget", () => {
     expect(result?.kind).toBe("reply");
   });
 
+  it("handles non-string reply text gracefully (issue #27201)", () => {
+    const result = describeReplyTarget({
+      message_id: 2,
+      date: 1000,
+      chat: { id: 1, type: "private" },
+      reply_to_message: {
+        message_id: 1,
+        date: 900,
+        chat: { id: 1, type: "private" },
+        // Simulate edge case where text is an unexpected non-string value
+        text: { some: "object" },
+        from: { id: 42, first_name: "Alice", is_bot: false },
+      },
+      // oxlint-disable-next-line typescript/no-explicit-any
+    } as any);
+    // Should not produce "[object Object]" — should return null (no valid body)
+    expect(result).toBeNull();
+  });
+
   it("extracts forwarded context from reply_to_message (issue #9619)", () => {
     // When user forwards a message with a comment, the comment message has
     // reply_to_message pointing to the forwarded message. We should extract

extensions/telegram/src/bot/helpers.ts

@@ -406,7 +406,8 @@ export function describeReplyTarget(msg: Message): TelegramReplyTarget | null {
 
   const replyLike = reply ?? externalReply;
   if (!body && replyLike) {
-    const replyBody = (replyLike.text ?? replyLike.caption ?? "").trim();
+    const rawText = replyLike.text ?? replyLike.caption ?? "";
+    const replyBody = (typeof rawText === "string" ? rawText : "").trim();
     body = replyBody;
     if (!body) {
       body = resolveTelegramMediaPlaceholder(replyLike) ?? "";