@netlify/plugin-nextjs fails with "Cannot find module"

[clareoneill]

Describe the bug
Next.js app build is failing with this error:

8:30:27 AM: ────────────────────────────────────────────────────────────────
8:30:27 AM:   Plugin "@netlify/plugin-nextjs" failed                        
8:30:27 AM: ────────────────────────────────────────────────────────────────
8:30:27 AM: 
8:30:27 AM:   Error message
8:30:27 AM:   Error: Error loading your next.config.js.
8:30:27 AM:   Cannot find module '@next/bundle-analyzer'
8:30:27 AM:   Require stack:
8:30:27 AM:   - /opt/build/repo/frontend/next.config.js
8:30:27 AM:   - /opt/build/repo/frontend/node_modules/next/dist/next-server/server/config.js
8:30:27 AM:   - /opt/build/repo/frontend/.netlify/plugins/node_modules/@netlify/plugin-nextjs/helpers/getNextConfig.js
8:30:27 AM:   - /opt/build/repo/frontend/.netlify/plugins/node_modules/@netlify/plugin-nextjs/index.js
8:30:27 AM:   - /opt/buildhome/.netlify-build-nvm/versions/node/v12.16.3/lib/node_modules/@netlify/build/src/plugins/child/logic.js
8:30:27 AM:   - /opt/buildhome/.netlify-build-nvm/versions/node/v12.16.3/lib/node_modules/@netlify/build/src/plugins/child/load.js
8:30:27 AM:   - /opt/buildhome/.netlify-build-nvm/versions/node/v12.16.3/lib/node_modules/@netlify/build/src/plugins/child/main.js

next.config.js

const hostname = new URL(process.env.WORDPRESS_URL).hostname;
const withBundleAnalyzer = require('@next/bundle-analyzer')({
  enabled: process.env.ANALYZE === 'true',
});

module.exports = withBundleAnalyzer({
  target: 'serverless',
  webpack: config => {
    config.module.rules.push({
      test: /\.svg$/,
      use: ['@svgr/webpack', 'url-loader'],
    });
    return config;
  },
  images: {
    domains: [hostname],
  },
});

netlify.toml

[build]
  base = "frontend/"
  command = "yarn build"
  publish = ".next"

[[plugins]]
  package = "@netlify/plugin-nextjs"

Versions

• next@10.2.3
• @netlify/plugin-nextjs@3.4.0

---

The last successful build happened 5/26 with these versions:

• next@10.2.3
• @netlify/build@11.22.0
• @netlify/plugin-nextjs@3.3.1

The first failed build happened 6/1 with these versions:

• next@10.2.3
• @netlify/build@11.29.2
• @netlify/plugin-nextjs@3.3.1

I tried to deploy the last successful build from 5/26 today and it failed with the same error with these versions:

• next@10.2.3
• @netlify/build@11.31.1
• @netlify/plugin-nextjs@3.4.0

I think the only thing that changed between the last successful deploy and when I tried to redeploy it are the @netlify/build and @netlify/plugin-nextjs versions.

[lindsaylevine]

@clareoneill hey claire! thanks for the detailed issue!! it seems like the only diff between the 5/26 successful build and 6/1 failed build is the netlify/build version, so i pinged some engineers internally. while we did only release 3.4.0 today, i can't rule out it being somewhat part of the issue. would it be possible to spin up a repo that reproduces the cannot find module error for us? that would be super helpful, though we do v much appreciate all the details already included!! 🙏

[clareoneill]

Figured it out! NODE_ENV was set to production so the devDependencies weren't being installed during the build 🤦🏻 Thanks for pointing me in the right direction.