I'm getting a very confusing parsing error when I run `git push heroku master` when trying to build a React app in Heroku that successfully built yesterday. The only changes since then have been some media queries another contributor added to several .scss files.

The main error (full build report listed below) reads, 
`remote: Failed to compile.
remote:
remote: Parse error on line 1: 
remote: ^
remote: Expecting "CALC", "LPAREN", "SUB", "NUMBER", "FUNCTION", "LENGTH", "ANGLE", "TIME", "FREQ", "RES", "EMS", "EXS", "CHS", "REMS", "VHS", "VWS", "VMINS", "VMAXS", "PERCENTAGE", "expression", "math_expression", "value", "function", "css_value", got unexpected end of input
remote: 
remote: 
remote: npm ERR! code ELIFECYCLE
remote: npm ERR! errno 1
remote: npm ERR! world-of-flags@0.1.0 build:`react-scripts build`remote: npm ERR! Exit status 1`

The most confusing part of this is that I can't figure out which file this error is referring to when it says `Parse error on line 1`. Based on reading this stack overflow question ([git push heroku master fails with parse error - which file?](https://stackoverflow.com/questions/21966019/git-push-heroku-master-fails-with-parse-error-which-file)) I assumed the error was referring to my package.json file. However, I can't find anything wrong with it. Any help on this would be greatly appreciated.

**package.json**

```js
{
  "name": "world-of-flags",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "dotenv": "^6.2.0",
    "enzyme": "^3.8.0",
    "node-sass": "^4.11.0",
    "prop-types": "^15.6.2",
    "react": "^16.6.3",
    "react-dom": "^16.6.3",
    "react-redux": "^6.0.0",
    "react-router-dom": "^4.3.1",
    "react-scripts": "^2.1.3",
    "redux": "^4.0.1",
    "redux-devtools-extension": "^2.13.7",
    "redux-thunk": "^2.3.0"
  },
  "jest": {
    "collectCoverageFrom": [
      "src/**/*.{js,jsx}",
      "!src/index.js",
      "!src/serviceWorker.js",
      "!src/setupTests.js",
      "!src/history.js",
      "!src/reducers/index.js",
      "!src/mockData/mockData.js",
      "!src/utilities/allCountries.js",
      "!src/utilities/allCountriesImagesObject.js",
      "!src/utilities/allCountriesObjects.js"
    ]
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject",
    "eslint": "./node_modules/eslint/bin/eslint.js ./src/*.js"
  },
  "eslintConfig": {
    "extends": "react-app"
  },
  "browserslist": [
    ">0.2%",
    "not dead",
    "not ie <= 11",
    "not op_mini all"
  ],
  "devDependencies": {
    "enzyme-adapter-react-16": "^1.7.1",
    "jshint": "^2.9.7",
    "prettier": "1.15.3",
    "resolve-url-loader": "^3.0.0"
  },
  "prettier": {
    "trailingComma": "es5",
    "tabWidth": 2,
    "semi": true,
    "singleQuote": true
  }
}
```

**Full Heroku build log**

```js
-----> React.js (create-react-app) multi app detected
-----> Configure create-react-app build environment
       Using `NODE_ENV=development`
=====> Downloading Buildpack: https://github.com/heroku/heroku-buildpack-multi.git
=====> Detected Framework: Multipack
=====> Downloading Buildpack: https://github.com/heroku/heroku-buildpack-nodejs.git
=====> Detected Framework: Node.js

-----> Creating runtime environment

       NPM_CONFIG_LOGLEVEL=error
       NPM_CONFIG_PRODUCTION=false
       NODE_ENV=development
       NODE_MODULES_CACHE=true
       NODE_VERBOSE=false

-----> Installing binaries
       engines.node (package.json):  unspecified
       engines.npm (package.json):   unspecified (use default)

       Resolving node version 10.x...
       Downloading and installing node 10.15.0...
       Using default npm version: 6.4.1

-----> Restoring cache
       - node_modules

-----> Building dependencies
       Installing node modules (package.json + package-lock)
       added 212 packages from 12 contributors, removed 4 packages, updated 98 packages and audited 36629 packages in 28.481s
       found 0 vulnerabilities

-----> Caching build
       - node_modules

-----> Pruning devDependencies
       Skipping because NODE_ENV is not 'production'

-----> Build succeeded!
=====> Downloading Buildpack: https://github.com/mars/create-react-app-inner-buildpack.git
=====> Detected Framework: React.js (create-react-app)
       Writing `static.json` to support create-react-app
       Enabling runtime environment variables
> world-of-flags@0.1.0 build /tmp/build_768ef9fd4678f7cb022271fe96647f94
> react-scripts build
Creating an optimized production build...
Failed to compile.
Parse error on line 1: 
^
Expecting "CALC", "LPAREN", "SUB", "NUMBER", "FUNCTION", "LENGTH", "ANGLE", "TIME", "FREQ", "RES", "EMS", "EXS", "CHS", "REMS", "VHS", "VWS", "VMINS", "VMAXS", "PERCENTAGE", "expression", "math_expression", "value", "function", "css_value", got unexpected end of input
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! world-of-flags@0.1.0 build: `react-scripts build`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the world-of-flags@0.1.0 build script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
npm ERR! A complete log of this run can be found in:
npm ERR!     /app/.npm/_logs/2019-01-19T21_04_11_353Z-debug.log
 !     Push rejected, failed to compile React.js (create-react-app) multi app.
 !     Push failed
```