Remove dependency on System.Console in Blazor WASM app

[eerhardt]

This is the first change necessary. It removes the one place that depends on Console.WriteLine.

This first change doesn't save much size (.br compressed):

• Before: 2,719,214 bytes
• After: 2,719,111 bytes

However, if we can also remove the last place that references System.Console, we should be able to trim the whole assembly (6KB .br compressed).

aspnetcore/src/Components/WebAssembly/WebAssembly/src/Hosting/EntrypointInvoker.cs

Lines 79 to 83 in dfe625f

	private static void HandleStartupException(Exception exception)
	{
	// Logs to console, and causes the error UI to appear
	Console.Error.WriteLine(exception);
	}

Speaking with @lewing, we thought if we unified the startup paths between the mono runtime and Blazor, we should be able to remove this last dependency on System.Console. @lewing was going to log an issue to track unifying the startup code.

cc @marek-safar

[Eilon]

I approve as a non-stakeholder.

[javiercn]

However, if we can also remove the last place that references System.Console, we should be able to trim the whole assembly

I think it could be doable, we would need to call some JS interop API instead to notify JS of the error. @SteveSandersonMS do you have any thoughts/concerns?

[eerhardt]

@captainsafia - any thoughts on this PR? I think it is ready to merge, unless you have other feedback.

[javiercn]

@eerhardt can we let @SteveSandersonMS comment on the last System.Console usage to see if we can just update this PR and trim the entire assembly?

[eerhardt]

if we can just update this PR and trim the entire assembly?

My understanding is to trim the entire System.Console assembly is going to take a bit of refactoring how we initialize a Blazor WASM app, and it may take coordination with @lewing's team.

[javiercn]

My understanding is to trim the entire System.Console assembly is going to take a bit of refactoring how we initialize a Blazor WASM app, and it may take coordination with @lewing's team.

Ah, thanks for the clarification.

Then let's get this merged!

Thanks for the PR

[javiercn]

@eerhardt do you want to merge the PR yourself or are you ok if we do it for you

[SteveSandersonMS]

Speaking with @lewing, we thought if we unified the startup paths between the mono runtime and Blazor, we should be able to remove this last dependency on System.Console. @lewing was going to log an issue to track unifying the startup code.

I'm sure we can remove the Console.Error.WriteLine call from HandleStartupException independently of any unification to the startup paths. Since that call is coming from the .WebAssembly assembly, it could directly call WebAssembly.JSInterop.InternalCalls.InvokeJS to get the log message into JS world.

Or if that's inconvenient, we could even have a dedicated InternalCall method specifically for logging errors, which would bypass all dependencies on any JS interop (and maybe there already is one).

[captainsafia]

Looks good from my end!

We can take Steve's recommendation on cleaning up the System.Console use in the entrypoint invoker and finish this off.