Fix status codes on internal error.

app.py

@@ -96,6 +96,7 @@ def set_style(style):
     return "", 204
 
 @app.errorhandler(404)
+@app.catch_exceptions
 def page_not_found(err):
     """Render and return the 404 error template."""
     return render_template("404.mako"), 404

calefaction/util.py

@@ -47,10 +47,11 @@ def make_error_catcher(app, error_template):
                 raise
             except TemplateError as exc:
                 app.logger.error("Caught exception:\n{0}".format(exc.text))
-                return render_template(error_template, traceback=exc.text)
+                trace = exc.text
             except Exception:
                 app.logger.exception("Caught exception:")
-                return render_template(error_template, traceback=format_exc())
+                trace = format_exc()
+            return render_template(error_template, traceback=trace), 500
         return inner
     return callback