Validate default Razor and Blazor project templates with nullability enforcement enabled doesn't result in unexpected warnings.

[NTaylorMullen]

• Open up all of the .cshtml files in a Razor pages site with nullability enforcement enabled and ensure that there are no warnings for nullability.
• Open up all of the .razor files in a Razor pages site with nullability enforcement enabled and ensure that there are no warnings for nullability.

[NTaylorMullen]

• Open up all of the .razor files in a Razor pages site with nullability enforcement enabled and ensure that there are no warnings for nullability.

@danroth27 there are several locations in our Blazor project templates that aren't nullable enforcement friendly. Is this something we want to address or leave as is? I'm uncertain of C#'s plans to turn the feature on by default or not so this decision might be largely based on that decision as well.

For context in Blazor server side app there's:

Shared\NavMenu.razor(31,31): warning CS8603: Possible null reference return. [C:\Users\nimullen.REDMOND\source\repos\Preview9BlazorServerSide\Preview9BlazorServerSide\Preview9BlazorServerSide.csproj]
Pages\FetchData.razor(40,23): warning CS8618: Non-nullable field 'forecasts' is uninitialized. Consider declaring the field as nullable. [C:\Users\nimullen.REDMOND\source\repos\Preview9BlazorServerSide\Preview9BlazorServerSide\Preview9BlazorServerSide.csproj]
Data\WeatherForecast.cs(13,23): warning CS8618: Non-nullable property 'Summary' is uninitialized. Consider declaring the property as nullable. [C:\Users\nimullen.REDMOND\source\repos\Preview9BlazorServerSide\Preview9BlazorServerSide\Preview9BlazorServerSide.csproj]
Data\WeatherForecast.cs(13,23): warning CS8618: Non-nullable property 'Summary' is uninitialized. Consider declaring the property as nullable. [C:\Users\nimullen.REDMOND\source\repos\Preview9BlazorServerSide\Preview9BlazorServerSide\Preview9BlazorServerSide.csproj]
Shared\NavMenu.razor(31,31): warning CS8603: Possible null reference return. [C:\Users\nimullen.REDMOND\source\repos\Preview9BlazorServerSide\Preview9BlazorServerSide\Preview9BlazorServerSide.csproj]
Pages\FetchData.razor(40,23): warning CS8618: Non-nullable field 'forecasts' is uninitialized. Consider declaring the field as nullable. [C:\Users\nimullen.REDMOND\source\repos\Preview9BlazorServerSide\Preview9BlazorServerSide\Preview9BlazorServerSide.csproj]
    6 Warning(s)

Blazor WASM:

Shared\SurveyPrompt.razor(14,31): warning CS8618: Non-nullable property 'Title' is uninitialized. Consider declaring the property as nullable. [C:\Users\nimullen.REDMOND\source\repos\Preview9BlazorWASM\Preview9BlazorWASM\Preview9BlazorWASM.csproj]
Shared\NavMenu.razor(31,31): warning CS8603: Possible null reference return. [C:\Users\nimullen.REDMOND\source\repos\Preview9BlazorWASM\Preview9BlazorWASM\Preview9BlazorWASM.csproj]
Pages\FetchData.razor(38,23): warning CS8618: Non-nullable field 'forecasts' is uninitialized. Consider declaring the field as nullable. [C:\Users\nimullen.REDMOND\source\repos\Preview9BlazorWASM\Preview9BlazorWASM\Preview9BlazorWASM.csproj]
Pages\FetchData.razor(51,23): warning CS8618: Non-nullable property 'Summary' is uninitialized. Consider declaring the property as nullable. [C:\Users\nimullen.REDMOND\source\repos\Preview9BlazorWASM\Preview9BlazorWASM\Preview9BlazorWASM.csproj]
Shared\SurveyPrompt.razor(14,31): warning CS8618: Non-nullable property 'Title' is uninitialized. Consider declaring the property as nullable. [C:\Users\nimullen.REDMOND\source\repos\Preview9BlazorWASM\Preview9BlazorWASM\Preview9BlazorWASM.csproj]
Pages\FetchData.razor(38,23): warning CS8618: Non-nullable field 'forecasts' is uninitialized. Consider declaring the field as nullable. [C:\Users\nimullen.REDMOND\source\repos\Preview9BlazorWASM\Preview9BlazorWASM\Preview9BlazorWASM.csproj]
Pages\FetchData.razor(51,23): warning CS8618: Non-nullable property 'Summary' is uninitialized. Consider declaring the property as nullable. [C:\Users\nimullen.REDMOND\source\repos\Preview9BlazorWASM\Preview9BlazorWASM\Preview9BlazorWASM.csproj]
Shared\NavMenu.razor(31,31): warning CS8603: Possible null reference return. [C:\Users\nimullen.REDMOND\source\repos\Preview9BlazorWASM\Preview9BlazorWASM\Preview9BlazorWASM.csproj]
    8 Warning(s)

[danroth27]

@NTaylorMullen We should address these, so go ahead and file an issue if you haven't already.

[NTaylorMullen]

Looks like I already filed an issue for this a while back that's in 3.1.0. Feel free to move the milestone if you want: #10921