Typings - Lack of optional parameters

[aistrych]

ForkTsCheckerWebpackPlugin require Option type as a parameter but all keys in it are required. For that reason user has to pass all options to the plugin which shouldn't be the case. What with default values? It's also impossible to cast passed object to Option type: Options interface is not exported. This is now impossible:

new ForkTsCheckerWebpackPlugin({
    tsconfig: "../../tsconfig.json",
    tslint: "../../tslint.json",
    watch: ["./app"],
    workers: ForkTsCheckerWebpackPlugin.TWO_CPUS_FREE
})

because Typescript emits:

[ts]
Argument of type '{ tsconfig: string; tslint: string; watch: string[]; workers: number; }' is not assignable to parameter of type 'Options'.
  Property 'async' is missing in type '{ tsconfig: string; tslint: string; watch: string[]; workers: number; }'.

After adding 'async' it starts to complain about other parameters.

I believe some keys in that interface should be optional:

interface Options {
  tsconfig: string;
  tslint: string | true;
  watch: string | string[];
  async: boolean;
  ignoreDiagnostics: number[];
  ignoreLints: string[];
  colors: boolean;
  logger: Console;
  formatter: 'default' | 'codeframe' | Formatter;
  formatterOptions: any;
  silent: boolean;
  checkSyntacticErrors: boolean;
  memoryLimit: number;
  workers: number;
  vue: boolean;
}

typescript version: 3.0.1

[johnnyreilly]

Sure - if you'd like to submit a PR we can get it in the next release?

[aistrych]

Ok, thanks. I will do it tomorrow.

[Larry1123]

Oh I just submitted a PR for this #141