Typescript - The keyword 'interface' is reserved

[imsys]

I'm beginner at TS, and converting some code to it.

I'm getting this error when I try to create an interface.

1:50:07 PM [vite] Internal server error: src/components/Modal.svelte:6:0 The keyword 'interface' is reserved
  Plugin: vite-plugin-svelte
  File: src/components/Modal.svelte
   4 |  
   5 |  
   6 |  interface IModal {
        ^
   7 |      open: typeof open;
   8 |      close: typeof close;

<script context="module" lang="ts">

import {onDestroy} from 'svelte';

interface IModal {
    open: typeof open;
    close: typeof close;
};

"type": "module",
"devDependencies": {
  "@sveltejs/vite-plugin-svelte": "^1.0.0-next.34",
  "@tsconfig/svelte": "^3.0.0",
  "autoprefixer": "^10.4.1",
  "postcss": "^8.4.5",
  "postcss-font-magician": "^3.0.0",
  "postcss-load-config": "^3.1.1",
  "postcss-preset-env": "^7.2.0",
  "postcss-scss": "^4.0.2",
  "sass": "^1.46.0",
  "svelte": "^3.44.3",
  "svelte-check": "^2.2.11",
  "svelte-navigator": "^3.1.5",
  "svelte-preprocess": "^4.10.1",
  "tslib": "^2.3.1",
  "typescript": "^4.5.4",
  "vite": "^2.7.10"
}

svelte.config.js

import preprocess from 'svelte-preprocess'

export default {
  preprocess: preprocess()
}

tsconfig.json

{
  "extends": "@tsconfig/svelte/tsconfig.json",
  "compilerOptions": {
    "target": "esnext",
    "module": "esnext",
    "useDefineForClassFields": true,
    "baseUrl": ".",
    "allowJs": true,
    "checkJs": true
  },
  "include": ["src/**/*.d.ts", "src/**/*.ts", "src/**/*.js", "src/**/*.svelte"]
}

vite.config.js

import { svelte } from '@sveltejs/vite-plugin-svelte'
import { defineConfig } from 'vite'

import autoprefixer from 'autoprefixer';
import presetEnv from 'postcss-preset-env';
import fontMagician from 'postcss-font-magician';

export default defineConfig(({ command, mode }) => {
  const isProduction = mode === 'production'
  return {
    root: "src",
    publicDir: "../dist",
    plugins: [svelte()],
    css: {
      postcss:{
        plugins: [
          autoprefixer(),
          presetEnv(),
          fontMagician()
        ]
      }

    },
    server: {
      port: 8080
    },
    build: {
      outDir: '../dist',
      minify: isProduction
    }
  }
})

[imsys]

Hmm,..
I decided to copy the folder of an existing working Svelte + TS project that have a very similar structure, and then pasted the same files, and now it is working. I don't really know what was the problem, but at least I got it working.
Thanks!