Webpack error when deploying to heroku (npm Exit Status 2) - heroku

Question

My team mates and I are trying to deploy to Heroku and we've been getting this confusing error/build failure several times over.
Ways we've already troubleshot include:
Making sure devDependencies are in Dependencies
Deleted and reinstalled Wepback
deleted the lock files
cleared the npm cache
Created a new heroku app and attempted to deploy there with a fresh start
None of these have worked and we'd really appreciate the help. Thanks!
remote: -----> Building dependencies
remote: Installing node modules (package.json + package-lock)
remote:
remote: > sensation-mapping#0.0.1 postinstall /tmp/build_165cca2bcbc98089b28e7f67a5aa96ab
remote: > webpack
remote:
remote: Hash: be40b95d0b5157875598
remote: Version: webpack 3.12.0
remote: Time: 1767ms
remote: Asset Size Chunks Chunk Names
remote: bundle.js 801 kB 0 [emitted] [big] main
remote: bundle.js.map 943 kB 0 [emitted] main
remote: [12] ./client/index.js 543 bytes {0} [built]
remote: + 24 hidden modules
remote:
remote: ERROR in ./client/index.js
remote: Module not found: Error: Can't resolve './components/App' in '/tmp/build_165cca2bcbc98089b28e7f67a5aa96ab/client'
remote: # ./client/index.js 11:11-38
remote: npm ERR! code ELIFECYCLE
remote: npm ERR! errno 2
remote: npm ERR! sensation-mapping#0.0.1 postinstall: `webpack`
remote: npm ERR! Exit status 2
remote: npm ERR!
remote: npm ERR! Failed at the sensation-mapping#0.0.1 postinstall script.
remote: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
remote:
remote: npm ERR! A complete log of this run can be found in:
remote: npm ERR! /tmp/npmcache.6UwNM/_logs/2018-06-07T02_48_08_002Z-debug.log
remote:
remote: -----> Build failed

Answer 1

Things you can do to try and resolve the issue:
Check log for any issues.
Check code for any missing references to modules that might be called but doesn't exist.
After doing the above steps try and build again and see what happens.