From 491091706f408049201edf76b74ae521b4463513 Mon Sep 17 00:00:00 2001
From: Bailey Ling <bling@live.ca>
Date: Sun, 6 Oct 2013 09:03:47 -0400
Subject: [PATCH] add guard for possible undefined window context (#276).

---
 autoload/airline.vim | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/autoload/airline.vim b/autoload/airline.vim
index c4c7d77..664c78e 100644
--- a/autoload/airline.vim
+++ b/autoload/airline.vim
@@ -120,7 +120,12 @@ function! s:invoke_funcrefs(context, funcrefs)
 endfunction
 
 function! airline#statusline(winnr)
-  return '%{airline#check_mode('.a:winnr.')}'.s:contexts[a:winnr].line
+  if has_key(s:contexts, a:winnr)
+    return '%{airline#check_mode('.a:winnr.')}'.s:contexts[a:winnr].line
+  endif
+
+  " in rare circumstances this happens...see #276
+  return ''
 endfunction
 
 function! airline#check_mode(winnr)