For usages of assert() that are meant to persist in Release builds (when NDEBUG is defined), replace those usages with persistent alternatives

src/chat.cpp

@@ -83,7 +83,7 @@ u32 ChatBuffer::getScrollback() const
 
 const ChatLine& ChatBuffer::getLine(u32 index) const
 {
-	assert(index < getLineCount());
+	assert(index < getLineCount());	// pre-condition
 	return m_unformatted[index];
 }
 
@@ -107,7 +107,8 @@ void ChatBuffer::deleteOldest(u32 count)
 		// keep m_formatted in sync
 		if (del_formatted < m_formatted.size())
 		{
-			assert(m_formatted[del_formatted].first);
+
+			sanity_check(m_formatted[del_formatted].first);
 			++del_formatted;
 			while (del_formatted < m_formatted.size() &&
 					!m_formatted[del_formatted].first)