Deploying Svelte App to Heroku / Dokku fails because modules cannot be found - node.js

Question

I am having problems deploying my svelte web3 App to my VPS running Dokku.
The structure of the folder is as follows:
root
|-->svelte
|--> ...
I found some solutions to work with the two folders needing npm install around here. So I put:
"heroku-postbuild": "cd ./svelte && npm install && npm run build" and "cacheDirectories": ["./node_modules", "./svelte/node_modules"] in the root package.json.
But when the process comes to this point it fails with the following error:
remote: [!] Error: Cannot find module '#rollup/plugin-node-resolve'
remote: Require stack:
remote: - /tmp/build/svelte/rollup.config.js
remote: - /tmp/build/svelte/node_modules/rollup/dist/shared/loadConfigFile.js
remote: - /tmp/build/svelte/node_modules/rollup/dist/bin/rollup
I've tried changing the import to include the full paths etc. but nothing has worked so far. I have also changed the order of the imports, but the process fails with the first import in the rollup.config.
Any ideas?
package.json root:
"scripts": {
"heroku-postbuild": "cd ./svelte && npm install && npm run build"
},
"dependencies": {
"#openzeppelin/contracts": "^4.6.0",
"#truffle/hdwallet-provider": "^2.0.8",
"babel-polyfill": "^6.26.0",
"babel-register": "^6.26.0",
"dotenv": "^16.0.0",
"web3": "^1.7.3"
},
"cacheDirectories": ["./node_modules", "./svelte/node_modules"],
"engines": {
"node": "16.14",
"npm": "8.7.x"
}
}
package.json svelte (added all the dev dependencies again just in case)
{
"name": "app",
"version": "1.0.0",
"private": true,
"scripts": {
"build": "rollup -c",
"dev": "rollup -c -w",
"start": "sirv public --no-clear"
},
"devDependencies": {
"#rollup/plugin-commonjs": "^17.0.0",
"#rollup/plugin-node-resolve": "^11.0.0",
"rollup": "^2.3.4",
"rollup-plugin-css-only": "^3.1.0",
"rollup-plugin-livereload": "^2.0.0",
"rollup-plugin-svelte": "^7.0.0",
"rollup-plugin-terser": "^7.0.0",
"svelte": "^3.0.0"
},
"dependencies": {
"rollup-plugin-terser": "^7.0.0",
"svelte": "^3.0.0",
"#rollup/plugin-commonjs": "^17.0.0",
"#rollup/plugin-node-resolve": "^11.0.0",
"rollup-plugin-css-only": "^3.1.0",
"rollup": "^2.3.4",
"rollup-plugin-svelte": "^7.0.0",
"#rollup/plugin-json": "^4.1.0",
"apexcharts": "^3.35.0",
"bootstrap": "^5.1.3",
"moment": "^2.29.2",
"rollup-plugin-copy": "^3.4.0",
"sirv-cli": "^2.0.0",
"svelte-web3": "^3.4.0"
}
}
rollup.config.js
import resolve from '#rollup/plugin-node-resolve';
import { nodeResolve } from '#rollup/plugin-node-resolve';
import svelte from 'node_modules/rollup-plugin-svelte';
import commonjs from 'node_modules/#rollup/plugin-commonjs';
import livereload from 'node_modules/rollup-plugin-livereload';
import { terser } from 'node_modules/rollup-plugin-terser';
import css from 'node_modules/rollup-plugin-css-only';
import json from 'node_modules/#rollup/plugin-json';
import copy from 'node_modules/rollup-plugin-copy'
const production = !process.env.ROLLUP_WATCH;
function serve() {
let server;
function toExit() {
if (server) server.kill(0);
}
return {
writeBundle() {
if (server) return;
server = require('child_process').spawn('npm', ['run', 'start', '--', '--dev'], {
stdio: ['ignore', 'inherit', 'inherit'],
shell: true
});
process.on('SIGTERM', toExit);
process.on('exit', toExit);
}
};
}
export default {
input: 'src/main.js',
output: {
sourcemap: true,
format: 'iife',
name: 'app',
file: 'public/build/bundle.js'
},
plugins: [
svelte({
compilerOptions: {
// enable run-time checks when not in production
dev: !production
}
}),
// we'll extract any component CSS out into
// a separate file - better for performance
css({ output: 'bundle.css' }),
// If you have external dependencies installed from
// npm, you'll most likely need these plugins. In
// some cases you'll need additional configuration -
// consult the documentation for details:
// https://github.com/rollup/plugins/tree/master/packages/commonjs
resolve({
browser: true,
dedupe: ['svelte']
}),
commonjs(),
json(),
nodeResolve(),
copy({
targets: [{
src: './node_modules/bootstrap/dist/**/*',
dest: 'public/vendor/bootstrap'
}]
}),
// In dev mode, call `npm run start` once
// the bundle has been generated
!production && serve(),
// Watch the `public` directory and refresh the
// browser on changes when not in production
!production && livereload('public'),
// If we're building for production (npm run build
// instead of npm run dev), minify
production && terser()
],
watch: {
clearScreen: false
}
};
```