no dispatchGlobalEventToAllElements when no renderer attached

[zuizuihao]

ROOT CAUSE

when Blazor connection closed, the detachWebRendererInterop in the callback of connection.onclose will be invoked. here, it will invoke interopMethodsByRenderer.delete(rendererId);, all the interopMethodsByRenderer will be cleaned. also There are lots of global event listener in form.js like window.addEventListener('focus'), window.addEventListener('keydown'). if user still interact with our app like focus, click, the global event will be triggered, then invoked EventDelegator.onGlobalEvent, invoked EventDelegator.dispatchGlobalEventToAllElements invoked WebRendererInteropMethods.dispatchEvent invoked WebRendererInteropMethods.getInteropMethods, here since the interopMethodsByRenderer is empty, will throw this exception.

SOLUTION:

check isRendererAttached before dispatchGlobalEventToAllElements in EventDelegator

Fixes #57828

Before Fixes:

After Fixes:

[dotnet-policy-service]

Thanks for your PR, @zuizuihao. Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[dotnet-policy-service]

Hi @zuizuihao. If this is not a tell-mode PR, please make sure to follow the instructions laid out in the servicing process document.
Otherwise, please add tell-mode label.

[dotnet-policy-service]

Looks like this PR hasn't been active for some time and the codebase could have been changed in the meantime.
To make sure no conflicting changes have occurred, please rerun validation before merging. You can do this by leaving an /azp run comment here (requires commit rights), or by simply closing and reopening.

[zuizuihao]

/azp run

[azure-pipelines]

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