id,node_id,number,title,user,state,locked,assignee,milestone,comments,created_at,updated_at,closed_at,author_association,pull_request,body,repo,type,active_lock_reason,performed_via_github_app,reactions,draft,state_reason
1618249044,I_kwDOBm6k_c5gdIVU,2038,Consider a `strict_templates` setting,9599,open,0,,,2,2023-03-10T02:09:13Z,2023-03-10T02:11:06Z,,OWNER,,"A setting which turns on Jinja strict mode, so any templates that access undefined variables raise a hard error.

Prototype here:
```diff
diff --git a/datasette/app.py b/datasette/app.py
index 40416713..1428a3f0 100644
--- a/datasette/app.py
+++ b/datasette/app.py
@@ -200,6 +200,7 @@ SETTINGS = (
         ""Allow display of SQL trace debug information with ?_trace=1"",
     ),
     Setting(""base_url"", ""/"", ""Datasette URLs should use this base path""),
+    Setting(""strict_templates"", False, ""Raise errors for undefined template variables""),
 )
 _HASH_URLS_REMOVED = ""The hash_urls setting has been removed, try the datasette-hashed-urls plugin instead""
 OBSOLETE_SETTINGS = {
@@ -399,11 +400,14 @@ class Datasette:
                 ),
             ]
         )
+        env_extras = {}
+        if self.setting(""strict_templates""):
+            env_extras[""undefined""] = StrictUndefined
         self.jinja_env = Environment(
             loader=template_loader,
             autoescape=True,
             enable_async=True,
-            undefined=StrictUndefined,
+            **env_extras,
         )
         self.jinja_env.filters[""escape_css_string""] = escape_css_string
         self.jinja_env.filters[""quote_plus""] = urllib.parse.quote_plus
```
Explored this idea a bit in:
- #1999",107914493,issue,,,"{""url"": ""https://api.github.com/repos/simonw/datasette/issues/2038/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,