Remove support for non-default typescript settings

[Zaczero]

Succeeds #1347

I agree with @timostamm and @smaye81 that we should not put effort into supporting non-default TypeScript features. Having said that, I noticed huge potential in removing redundant code that was there to make it "strict"-friendlier. This avoids a huge bug surface and typing misuse which the previous PR was trying to fix. So we get less code, and fewer bugs, and easier maintenance. Win-win-win!

https://www.typescriptlang.org/docs/handbook/compiler-options.html#strict-boolean-default-false

I'll soon do a broader sweep to remove unnecessary code, but this seems like a good first quick win!

[timostamm]

To clarify: We only support the standard compiler settings, emitted by tsc --init.

This PR introduces at least one major breaking change without without any apparent benefit and cannot be accepted.

If this was a sincere attempt to improve the project, I encourage you to become a bit more familiar with it first.

[Zaczero]

@timostamm The clarification still doesn't make sense.

Both are present by default in tsc --init.

{
  // Visit https://aka.ms/tsconfig to read more about this file
  "compilerOptions": {
    // File Layout
    // "rootDir": "./src",
    // "outDir": "./dist",

    // Environment Settings
    // See also https://aka.ms/tsconfig/module
    "module": "nodenext",
    "target": "esnext",
    "types": [],
    // For nodejs:
    // "lib": ["esnext"],
    // "types": ["node"],
    // and npm install -D @types/node

    // Other Outputs
    "sourceMap": true,
    "declaration": true,
    "declarationMap": true,

    // Stricter Typechecking Options
    "noUncheckedIndexedAccess": true,
    "exactOptionalPropertyTypes": true,

    // Style Options
    // "noImplicitReturns": true,
    // "noImplicitOverride": true,
    // "noUnusedLocals": true,
    // "noUnusedParameters": true,
    // "noFallthroughCasesInSwitch": true,
    // "noPropertyAccessFromIndexSignature": true,

    // Recommended Options
    "strict": true,
    "jsx": "react-jsx",
    "verbatimModuleSyntax": true,
    "isolatedModules": true,
    "noUncheckedSideEffectImports": true,
    "moduleDetection": "force",
    "skipLibCheck": true,
  }
}

I understand that the union with undefined is somewhat inelegant. However, misusing the optional operator is simply a typing bug, and now the library is becoming opinionated instead of following recommended best practices.

[timostamm]

If this is the default config that tsc emits, it has changed behavior recently-ish, and we should re-evaluate the situation.

Can you file an issue with details?