aspnetcore: Failed to start platform. Reason: [object ProgressEvent]

Describe the bug

Often times when I start my client side blazor app the browser console throws Failed to start platform. Reason: [object ProgressEvent] and the app never loads. Just stays on the splash screen.

To Reproduce

I wish I could confidently reproduce this but it just happens sometimes, and a few browser refreshes makes it work again.

Screenshots

Additional context

Using FireFox 69.0b3

.NET Core SDK (reflecting any global.json): Version: 3.0.100-preview6-012264 Commit: be3f0c1a03

Runtime Environment: OS Name: Windows OS Version: 10.0.18362 OS Platform: Windows RID: win10-x64 Base Path: C:\Program Files\dotnet\sdk\3.0.100-preview6-012264\

Host (useful for support): Version: 3.0.0-preview6-27804-01 Commit: fdf81c6faf

.NET Core SDKs installed: 2.1.700 [C:\Program Files\dotnet\sdk] 2.1.800-preview-009696 [C:\Program Files\dotnet\sdk] 3.0.100-preview6-012264 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed: Microsoft.AspNetCore.All 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All] Microsoft.AspNetCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 3.0.0-preview6.19307.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.NETCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 3.0.0-preview6-27804-01 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.WindowsDesktop.App 3.0.0-preview6-27804-01 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]