Merge pull request #976 from riganti/bugfix/better-error-corrupted-ma…

…sterpage Improved error reporting for corrupted master page
riganti · Apr 9, 2021 · fad57d9 · fad57d9
2 parents 79074ab + 2671043
commit fad57d9
Showing 1 changed file with 8 additions and 1 deletion.
diff --git a/src/DotVVM.Framework/Compilation/ControlTree/ControlTreeResolverBase.cs b/src/DotVVM.Framework/Compilation/ControlTree/ControlTreeResolverBase.cs
@@ -208,7 +208,14 @@ protected virtual void ValidateMasterPage(IAbstractTreeRoot root, IAbstractContr
             if (masterPage == null)
                 return;
             var viewModel = root.DataContextTypeStack.DataContextType;
-            if (!masterPage.DataContextType.IsAssignableFrom(viewModel))
+
+            if (masterPage.DataContextType is ResolvedTypeDescriptor typeDescriptor && typeDescriptor.Type == typeof(UnknownTypeSentinel))
+            {
+                masterPageDirective!.DothtmlNode!.AddError("Could not resolve the type of viewmodel for the specified master page. " +
+                    $"This usually means that there is an error with the @viewModel directive in the master page file: \"{masterPage.FileName}\". " +
+                    $"Make sure that the provided viewModel type is correct and visible for DotVVM.");
+            }
+            else if (!masterPage.DataContextType.IsAssignableFrom(viewModel))
             {
                 masterPageDirective!.DothtmlNode!.AddError($"The viewmodel {viewModel.Name} is not assignable to the viewmodel of the master page {masterPage.DataContextType.Name}.");
             }