fix(insomnia-test): expect actual render-error preview for custom template option

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

packages/insomnia-test/tests/environment/variable-source-live-preview/variable-source-modal-editing.spec.ts

@@ -32,7 +32,7 @@ test("Verify the tag modal's source follows the edited template and hides for no
   );
   await variableSourceFlow.selectModalVariable(
     { label: "-- Custom --" },
-    "my%20custom%20template%20logic",
+    "Failed to render environment variables: 'my custom template logic'",
   );
   const plainText = await variableSourceFlow.setModalTemplate("plain text", "plain text");
   const inheritedKey = await variableSourceFlow.setModalTemplate("{{ constructor }}");