For JavaScript Projects, Mark Unreachable Code as a Warning Instead of an Error

[mjbvz]

From microsoft/vscode#26016

Feature Request
Using the TypeScript 2.3 checkJs feature, we've seen a few requests in VSCode to downgrade the unreachable code error's severity from error to warning

I'm not sure if we should downgrade this error specifically, but I do think we should allow users to configure this. I believe that #6802 and #13408 track this

[mjbvz]

There are currently no workarounds to mark this error as a warning but you can suppress the error entirely using // @ts-ignore:

function foo(){
    return 1;
    // @ts-ignore
    return 2;
    return 3;
}

or for an entire project by creating a jsconfig.json at the root of your workspace that sets allowUnreachableCode:

{
    "compilerOptions": {
        "checkJs": true,
        "allowUnreachableCode": true
    },
    "exclude": [
        "node_modules"
    ]
}

[mhegazy]

The overarching issue of treeing specific errors as warnings is tracked by #13408. For this unreachable code specifically, @mjbvz's comment provide remedies.

[mhegazy]

closing in favor of #13408.