From 9944bb7048458fed0c096a5f77baaa369935cec6 Mon Sep 17 00:00:00 2001
From: Tom Christie <tom@tomchristie.com>
Date: Sat, 23 Feb 2019 17:49:07 +0000
Subject: [PATCH] Graceful error when using Jinja2Templates, but jinja2 is not
 installed

---
 starlette/templating.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/starlette/templating.py b/starlette/templating.py
index 5595364b..488d8c65 100644
--- a/starlette/templating.py
+++ b/starlette/templating.py
@@ -49,6 +49,7 @@ class Jinja2Templates:
     """
 
     def __init__(self, directory: str) -> None:
+        assert jinja2 is not None, "jinja2 must be installed to use Jinja2Templates"
         self.env = self.get_env(directory)
 
     def get_env(self, directory: str) -> "jinja2.Environment":