tsconfig.json

{
    "extends": "@tsconfig/svelte/tsconfig.json",
    "compilerOptions": {
        "target": "ESNext",
        "useDefineForClassFields": true,
        "module": "ES6",
        "resolveJsonModule": true,
        "allowJs": true,
        "isolatedModules": true,
        "noEmitOnError": true,
        "plugins": [
            {
                "name": "typescript-svelte-plugin",
                // the following options can be set additionally; they are optional; their default values are listed here
                "enabled": true, // enables this plugin
                "assumeIsSvelteProject": true // if true, skip detection and always assume it's a Svelte project
            }
        ]
    },
    "include": ["src/**/*.d.ts", "src/**/*.ts", "src/**/*.js", "src/**/*.svelte"]
}