core: fix infinite loop in display when the chat area is too small (closes #2053)

ChangeLog.adoc

@@ -40,6 +40,7 @@ New features::
 
 Bug fixes::
 
+  * core: fix infinite loop in display when the chat area is too small (issue #2053)
   * core: fix value of buffer variable "num_history" when the value defined in option weechat.history.max_commands is reached
   * core: remove incorrect warning when binding keys kbd:[F10] to kbd:[F20] (issue #2039)
   * core: call hook config when options are removed

src/gui/curses/gui-curses-chat.c

@@ -645,6 +645,8 @@ gui_chat_display_word (struct t_gui_window *window,
                                                               nick_offline);
             }
             ptr_data[pos_saved_char] = saved_char;
+            if (pos_saved_char == 0)
+                break;
             ptr_data += pos_saved_char;
         }
         else
@@ -666,6 +668,8 @@ gui_chat_display_word (struct t_gui_window *window,
                                                               apply_style_inactive,
                                                               nick_offline);
             }
+            if (!ptr_data[0])
+                break;
             ptr_data += strlen (ptr_data);
         }