tsconfig.json

{
    "compilerOptions": {
        // @see https://github.com/sveltejs/language-tools/blob/master/docs/preprocessors/typescript.md#getting-it-to-work-for-your-build 
        "moduleResolution": "node",
        "target": "es2017",
        //This fixes wrong code line highlighting (svelte errors)!
        "sourceMap": true,

        // This should be irelevant as we're compiling via Rollup, not tsc, default is false
        //"allowJs": false,

        // I see no difference / impact when setting "strict" true / false, default is false, leave it.
        //"strict": false,

        // It works with 'rollup-plugin-typescript2' but then importing Sv3InputTypes.ts "fails"
        // @see https://github.com/ezolenko/rollup-plugin-typescript2/issues/172

        // The attempt to export *.d.ts from *.svelte ts-code failed, see rollup.config.
        // @see https://github.com/rollup/plugins/issues/243
        // @see https://github.com/supermacro/neverthrow/pull/60
        // TODO: Keep an eye on how to emit a d.ts files from a .svelte component using typescript.
        // I believe this is currently not possible. (?)
        
        /*
        "declaration": true,
        "declarationDir": "./dist/types",
        "emitDeclarationOnly": true,
        "rootDir": "./src",
        */

        // Emitting *.d.ts only via tsc
        /*
        "declaration": true,
        "emitDeclarationOnly": true,
        */
        
        // @see https://stackoverflow.com/questions/43874096/difference-in-the-lib-property-in-tsconfig-json-between-es6-and-es2017/43892665#43892665
        
        // commented out trying to fix bundle bug 
        /*"lib": [
            //trying to fix bundle bug (importing from .mjs)
            "es2017", "DOM"
        ],*/

        "types": [
            "svelte"
        ],
        "baseUrl": "."
    },
    "include": [
        "src/**/*"
      ],
    "exclude": [
        "node_modules/*", "dist/*"
    ]
}