Exception thrown intermittently, custom MudBlazor theme with WASM

[TomasEvansCode]

Hi,

I'm creating an app with a custom MudBlazor theme (Based on Leigh Pointer's theme template) using Oqtane 6.1.0, and running in WASM.

The app works fine immediately after building and running from IDE (Visual Studio or Rider), but upon page reload I sometimes get one of the following exceptions:

(ThemeBuilder.razor:66)

blazor.web.js:1 crit: Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]
      Unhandled exception rendering component: The component type must implement Microsoft.AspNetCore.Components.IComponent.
System.ArgumentException: The component type must implement Microsoft.AspNetCore.Components.IComponent.
   at Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder.OpenComponent(Int32 sequence, Type componentType)
   at Oqtane.UI.ThemeBuilder.<OnParametersSet>b__9_0(RenderTreeBuilder builder) in C:\git\DragRaceApp\oqtane.framework\Oqtane.Client\UI\ThemeBuilder.razor:line 66
   at Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder.AddContent(Int32 sequence, RenderFragment fragment)
   at Oqtane.UI.ThemeBuilder.BuildRenderTree(RenderTreeBuilder __builder)
   at Microsoft.AspNetCore.Components.ComponentBase.<.ctor>b__7_0(RenderTreeBuilder builder)
   at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment, Exception& renderFragmentException)

fail: Microsoft.AspNetCore.Components.Web.ErrorBoundary[0]
      System.IO.FileNotFoundException: Could not load file or assembly 'MudBlazor, Version=8.2.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies.
      File name: 'MudBlazor, Version=8.2.0.0, Culture=neutral, PublicKeyToken=null'
         at Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder.AddContent(Int32 sequence, RenderFragment fragment)
         at Microsoft.AspNetCore.Components.Web.ErrorBoundary.BuildRenderTree(RenderTreeBuilder builder)
         at Microsoft.AspNetCore.Components.ComponentBase.<.ctor>b__7_0(RenderTreeBuilder builder)
         at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment, Exception& renderFragmentException)
System.IO.FileNotFoundException: Could not load file or assembly 'MudBlazor, Version=8.2.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies.
File name: 'MudBlazor, Version=8.2.0.0, Culture=neutral, PublicKeyToken=null'
   at Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder.AddContent(Int32 sequence, RenderFragment fragment)
   at Microsoft.AspNetCore.Components.Web.ErrorBoundary.BuildRenderTree(RenderTreeBuilder builder)
   at Microsoft.AspNetCore.Components.ComponentBase.<.ctor>b__7_0(RenderTreeBuilder builder)
   at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment, Exception& renderFragmentException)

This does not occur in Server render mode.

Whatever is causing this seems to be randomly determined when building my solution. A build that throws the exception will always do so if stopped and run again, and one that doesn't never will.

I'm not sure if this is an Oqtane issue, but I thought it may be worth asking here anyway as I'm aware that Oqtane may handle assemblies in a custom way and I'm not an expert on the Blazor + Oqtane WASM infrastructure.

My site settings:

I've tried the following with no success:

• Ensuring the relevant assemblies (MudBlazor.dll) are copied over in debug.cmd and exist in Oqtane.Server/bin/Debug/net9.0/
• Adding "MudBlazor" to the dependencies in my ITheme
• Building and running from different IDEs (Visual Studio 2022 and Rider)
• Browser hard reload / clear cache
• Deleting obj + bin directories
• Clean + rebuild solution
• dotnet-cleanup tool

Many thanks, any hints as to what I could investigate next would be much appreciated.

[TomasEvansCode]

I think I've managed to come up with some steps to replicate the issue:

1. Fresh download of Oqtane 6.1.0, build, run and install
2. Set site render mode to Interactive and runtime to WebAssembly
3. Create new theme from Oqtane theme admin UI
4. In the theme client project, install any library from nuget, make sure it is copied in debug.cmd to Oqtane.Server/bin/Debug/net9.0 and add to ThemeInfo dependencies
5. (Important) Reference the library somehow in the Theme.razor. (Add a @using and call a function or reference something from the library. In OnInitializedAsync() for example.)
6. Assign the new theme in Oqtane admin UI and save changes
7. When refreshing any page, an exception Could not load file or assembly may happen. If it doesn't, rebuild the theme solution and try again (Seems to happen around 50% of the time for me)

[TomasEvansCode]

I now believe this may be an Oqtane bug so have created an issue: #5103 (comment)