Can't deploy to heroku

## ❓Question

I cannot get heroku to pass my build using razzle. I've installed razzle-heroku. I've shifted to yarn. I have a yarn.lock file in both root and my app folder.
My project has a node server and a razzle/react client/server combo.

./package.json
```
{
"name": "charlierowat.com",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"start": "node server/index.js",
"dev": "nodemon server/index.js",
"heroku-postbuild": "cd app && yarn install && yarn build"
},
"proxy": "localhost:3001",
"repository": {
"type": "git",
"url": "git+https://github.com/rcrcr-omni/charlesrowat.co.uk.git"
},
"keywords": [],
"author": "",
"license": "ISC",
"bugs": {
"url": "https://github.com/rcrcr-omni/charlesrowat.co.uk/issues"
},
"homepage": "https://github.com/rcrcr-omni/charlesrowat.co.uk#readme",
"dependencies": {
"@babel/plugin-proposal-class-properties": "^7.18.6",
"@babel/preset-env": "^7.20.2",
"@babel/preset-react": "^7.18.6",
"@tanstack/react-query": "^4.19.1",
"@ungap/structured-clone": "^1.0.1",
"aws-sdk": "^2.1275.0",
"axios": "^1.1.3",
"babel-plugin-transform-assets": "^1.0.2",
"cors": "^2.8.5",
"create-razzle-app": "^4.2.18",
"dotenv": "^16.0.3",
"express": "^4.18.2",
"google-spreadsheet": "^3.3.0",
"ignore-styles": "^5.0.1",
"nodemon": "^2.0.20",
"react-dom": "^18.2.0",
"react-router-dom": "^6.6.1",
"serialize-javascript": "^6.0.0",
"sitemap": "^7.1.1"
},
"devDependencies": {
"@babel/register": "^7.18.9"
}
}
```

/app/package.json
```
{
"name": "charlierowat.com",
"version": "1.0.1",
"license": "MIT",
"proxy": "localhost:3000",
"scripts": {
"start": "razzle start",
"build": "razzle build",
"export": "razzle export",
"test": "razzle test --env=jsdom",
"start:static": "serve -s build/public",
"start:prod": "NODE_ENV=production node build/server.js"
},
"dependencies": {
"express": "^4.17.1",
"razzle-heroku": "^3.0.0",
"react": "^17.0.1",
"react-dom": "^17.0.1",
"react-ga4": "^1.4.1",
"react-helmet": "^6.1.0",
"react-markdown": "^6.0.3",
"react-router-dom": "^5.1.2"
},
"devDependencies": {
"babel-preset-razzle": "4.2.15",
"html-webpack-plugin": "^4.5.2",
"mini-css-extract-plugin": "^0.9.0",
"razzle": "4.2.15",
"razzle-dev-utils": "4.2.15",
"serve": "^11.3.2",
"webpack": "^4.44.1",
"webpack-dev-server": "^3.11.2"
}
}
```

**Error** (from heroku-postbuild)
```
remote: -----> Build
remote: Running heroku-postbuild (yarn)
remote: yarn run v1.22.19
remote: $ cd app && yarn install && yarn build
remote: [1/4] Resolving packages...
remote: [2/4] Fetching packages...
remote: [3/4] Linking dependencies...
remote: warning " > react-markdown@6.0.3" has unmet peer dependency "@types/react@>=16".
remote: warning "razzle > babel-jest@26.6.3" has unmet peer dependency "@babel/core@^7.0.0".
remote: warning "razzle > babel-loader@8.3.0" has unmet peer dependency "@babel/core@^7.0.0".
remote: warning "razzle > babel-jest > babel-preset-jest@26.6.2" has unmet peer dependency "@babel/core@^7.0.0".
remote: warning "razzle > babel-jest > babel-preset-jest > babel-preset-current-node-syntax@1.0.1" has unmet peer dependency "@babel/core@^7.0.0".
remote: warning "razzle > babel-jest > babel-preset-jest > babel-preset-current-node-syntax > @babel/plugin-syntax-import-meta@7.10.4" has unmet peer dependency "@babel/core@^7.0.0-0".
remote: [4/4] Building fresh packages...
remote: $ razzle build
remote: /bin/sh: 1: razzle: not found
remote: error Command failed with exit code 127.
remote: info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
remote: error Command failed with exit code 127.
remote: info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
remote:
remote: -----> Build failed
remote:
remote: We're sorry this build is failing! You can troubleshoot common issues here:
remote: https://devcenter.heroku.com/articles/troubleshooting-node-deploys
remote:
remote: Some possible problems:
remote:
remote: - node_modules checked into source control
remote: https://devcenter.heroku.com/articles/node-best-practices#only-git-the-important-bits
remote:
remote: - Node version not specified in package.json
remote: https://devcenter.heroku.com/articles/nodejs-support#specifying-a-node-js-version
remote:
remote: Love,
remote: Heroku
remote:
remote: ! Push rejected, failed to compile Node.js app.
remote:
remote: ! Push failed
remote: Verifying deploy...
remote:
remote: ! Push rejected to charliepersonalwebsite.
```

I would appreciate any help as razzle is the only way I've managed to get server side rendering working. Locally, at least!

Review package.json and app/package.json, starting with the heroku-postbuild command and the logged razzle build failure. Verify the deployment's dependency and build entry points using the Heroku output; done means the postbuild completes and the application deploys.

Written by the indexing model from the issue text.