[blazor] Add parameter to ErrorBoundary to let it render ChildContent when an exception was thrown

[zachneu]

This is extending ErrorBoundary for handling exceptions in Blazor without being forced to render something else (by using ErrorContent) than the component that throw the exception. This is to:

• Keep the component state if for example a "click to save" action fails
• Partly render the component if for example it fails to load data

It can be used like
<ErrorBoundary RenderOnException="true">...</ErrorBoundary>

Or your own component with custom OnErrorAsync like
<ErrorBoundaryTest RenderOnException="true">...</ErrorBoundaryTest>
##66214

[zachneu]

@dotnet-policy-service agree

[javiercn]

Thanks for the contribution @zachneu! We appreciate your interest in improving the ErrorBoundary component.

However, per our contribution policy, we ask that contributors file an issue and discuss the design with the team before submitting a pull request. Specifically:

If you would like to make a contribution to an area not documented here, first open an issue with a description of the change you would like to make and the problem it solves so it can be discussed before a pull request is submitted.

Additionally, for feature work like this, we encourage you to file a design proposal issue so the team can review the approach before significant effort is invested:

You find an existing issue with the "help-wanted" label or discuss with the team to agree on adding a new issue with that label. You post a high-level description of how it will be implemented and receive a positive acknowledgement from the team before getting too committed to the approach or investing too much effort in implementing it.

Could you please open an issue describing the scenario and proposed design so the team can discuss it first?

[zachneu]

Thanks for the contribution @zachneu! We appreciate your interest in improving the ErrorBoundary component.

However, per our contribution policy, we ask that contributors file an issue and discuss the design with the team before submitting a pull request. Specifically:

If you would like to make a contribution to an area not documented here, first open an issue with a description of the change you would like to make and the problem it solves so it can be discussed before a pull request is submitted.

Additionally, for feature work like this, we encourage you to file a design proposal issue so the team can review the approach before significant effort is invested:

You find an existing issue with the "help-wanted" label or discuss with the team to agree on adding a new issue with that label. You post a high-level description of how it will be implemented and receive a positive acknowledgement from the team before getting too committed to the approach or investing too much effort in implementing it.

Could you please open an issue describing the scenario and proposed design so the team can discuss it first?

Yes, @javiercn I can do that, but this have been something that has been asked for many places for long time, so I though to investigate what would be required to actually solve this, instead of spending time on open an issue, as the current version of errorboundary is basically useless for our needs.

[zachneu]

#66214