From e77a7e09bbde3215d18779d448792192f7dc7f3e Mon Sep 17 00:00:00 2001
From: Michael Kirk <michael.code@endoftheworl.de>
Date: Thu, 28 Sep 2017 09:31:17 -0400
Subject: [PATCH] Fix assert for empty thread

// FREEBIE
---
 .../ConversationView/ConversationViewController.m             | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Signal/src/ViewControllers/ConversationView/ConversationViewController.m b/Signal/src/ViewControllers/ConversationView/ConversationViewController.m
index 3c16f23ef..5a8e792d8 100644
--- a/Signal/src/ViewControllers/ConversationView/ConversationViewController.m
+++ b/Signal/src/ViewControllers/ConversationView/ConversationViewController.m
@@ -4075,6 +4075,10 @@ typedef NS_ENUM(NSInteger, MessagesRangeSizeMode) {
 
     uint64_t lastVisibleTimestamp = self.lastVisibleTimestamp;
 
+    if (lastVisibleTimestamp == 0) {
+        // No visible messages yet. New Thread.
+        return;
+    }
     [OWSReadReceiptManager.sharedManager markAsReadLocallyBeforeTimestamp:lastVisibleTimestamp thread:self.thread];
 }