Emit a more helpful error if INERTIA_LAYOUT is unset

inertia/http.py

@@ -3,6 +3,7 @@
 from json import dumps as json_encode
 
 import requests
+from django.core.exceptions import ImproperlyConfigured
 from django.http import HttpResponse
 from django.template.loader import render_to_string
 
@@ -127,10 +128,19 @@ def build_merge_props(self):
     def build_first_load(self, data):
         context, template = self.build_first_load_context_and_template(data)
 
+        try:
+            layout = settings.INERTIA_LAYOUT
+            if not layout:
+                raise AttributeError("INERTIA_LAYOUT is set, but has a falsy value")
+        except AttributeError as ae:
+            raise ImproperlyConfigured(
+                "INERTIA_LAYOUT must be set in your Django settings"
+            ) from ae
+
         return render_to_string(
             template,
             {
-                "inertia_layout": settings.INERTIA_LAYOUT,
+                "inertia_layout": layout,
                 **context,
             },
             self.request,

inertia/tests/test_rendering.py

@@ -1,3 +1,5 @@
+from django.core.exceptions import ImproperlyConfigured
+from django.test import override_settings
 from pytest import warns
 
 from inertia.test import InertiaTestCase, inertia_div, inertia_page
@@ -245,3 +247,12 @@
                 },
             ),
         )
+
+
+class MisconfiguredLayoutTestCase(InertiaTestCase):
+    def test_with_props(self):
+        with override_settings(INERTIA_LAYOUT=None), self.assertRaisesMessage(
+            ImproperlyConfigured,
+            "INERTIA_LAYOUT must be set",
+        ):
+            self.client.get("/props/")