svelte - `npm run build` will get the "unexpected token <" error

Question

After done with my development, I run npm run build to build the production app. but I will get:

Uncaught SyntaxError: Unexpected token '<'

from bundle.js .

I am running on svelte 3.0.0 . How can I resolve this?

Update1

Below is my rollup.config.js :

import svelte from 'rollup-plugin-svelte';
import resolve from '@rollup/plugin-node-resolve';
import commonjs from '@rollup/plugin-commonjs';
import livereload from 'rollup-plugin-livereload';
import { terser } from 'rollup-plugin-terser';

import preprocess from 'svelte-preprocess';

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({
            dev: !production,

            preprocess: preprocess(),
            css: css => {
                css.write('bundle.css');
            }

        }),
        resolve({
            browser: true,
            dedupe: ['svelte']
        }),
        commonjs(),

        !production && serve(),

        !production && livereload('public'),

        production && terser()
    ],
    watch: {
        clearScreen: false
    }
};

I don't quite remember, but I believe the only changes I made is all that related to preprocess for the css part.

Update2 I just test with the new svelte project without touching anything. I practically follow the instructions from the website:

npx degit sveltejs/template my-svelte-project
cd my-svelte-project

npm install
npm run build

the only different is I run build rather than dev . and immediately already got the same error:

bundle.js:1 Uncaught SyntaxError: Unexpected token '<'

below is the rollup.config.js :

import svelte from 'rollup-plugin-svelte';
import commonjs from '@rollup/plugin-commonjs';
import resolve from '@rollup/plugin-node-resolve';
import livereload from 'rollup-plugin-livereload';
import { terser } from 'rollup-plugin-terser';
import css from 'rollup-plugin-css-only';

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
            }
        }),
        css({ output: 'bundle.css' }),

        resolve({
            browser: true,
            dedupe: ['svelte']
        }),
        commonjs(),

        !production && serve(),

        !production && livereload('public'),

        production && terser()
    ],
    watch: {
        clearScreen: false
    }
};

Other than taking out the comments, all the code is the brand new from the download.

How can I resolve this issue?

Answer 1

Try using latest node version.

For example:

nvm install 14.17.5
nvm use 14.17.5

nvm github: https://github.com/nvm-sh/nvm

You can use n also: https://github.com/mklement0/n-install