Based on the issue referenced in @NikoSams answer, you just need to add "allowUnreachableCode": true to your tsconfig.json and it won't automatically remove dead code; you don't need to completely disable fixes on file save.

It's not listed as a setting because the extension at fault is the built-in typescript extension, and it gets its "settings" from your tsconfig.json, if present.

{
    "compilerOptions": {
        "allowUnreachableCode": true,
        ...
    },
    ...
}