fix: add null safety for tmux pane id handling

Tmux pane ID can be nil when inside of floating pane

Author: deathbeam

lua/tmux/layout/init.lua

@@ -72,7 +72,7 @@ function M.is_border(direction)
 
     local display = tmux.get_window_layout()
     local id = tmux.get_current_pane_id()
-    local result = check_is_border(display, id, direction)
+    local result = id and check_is_border(display, id, direction)
 
     log.debug("is_border > ", result or "false")
 

lua/tmux/wrapper/tmux.lua

@@ -75,7 +75,8 @@ function M.get_buffer_names()
 end
 
 function M.get_current_pane_id()
-    return tonumber(get_tmux_pane():sub(2))
+    local pane = get_tmux_pane()
+    return pane and tonumber(pane:sub(2)) or nil
 end
 
 function M.get_window_layout()