Deploy To Heroku Breaks App (Node, Yarn, Webpack 3, Angular 1.6) - angularjs

Question

I've been learning Webpack to transition from Bower. I've built a basic Angular(1.6.6) app on NodeJS(8.9.1) using Webpack(3.8.1) and Yarn(1.3.2); however, I get "Internal Server Error" when run on Heroku. Deploys fine, though, and works perfectly in localhost.
In my research, I've learned that Webpack needs to be in dependencies instead of devDependencies. Fixing this may have prevented other errors, but I have the same problem.
Heroku logs blame ejs, but I doubt that is the real problem:
Error: Could not find include include file.
at includeSource (/app/node_modules/ejs/lib/ejs.js:276:17)
at getIncludePath (/app/node_modules/ejs/lib/ejs.js:152:13)
at /app/node_modules/ejs/lib/ejs.js:629:26
at Array.forEach ()
at Template.generateSource (/app/node_modules/ejs/lib/ejs.js:605:15)
at Template.compile (/app/node_modules/ejs/lib/ejs.js:509:12)
at Object.compile (/app/node_modules/ejs/lib/ejs.js:358:16)
at handleCache (/app/node_modules/ejs/lib/ejs.js:201:18)
at tryHandleCache (/app/node_modules/ejs/lib/ejs.js:223:14)
at View.exports.renderFile [as engine]
(/app/node_modules/ejs/lib/ejs.js:437:10)
My package.json:
{ "name": "Simple Project",
"version": "0.1.0",
"description": "Simple Project",
"main": "server.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"build": "webpack",
"start": "node server.js",
"postinstall": "webpack -p",
"heroku-prebuild": "webpack -p"
},
"repository": {
"type": "git",
"url": "git+https://github.com/Simple/Project.git"
},
"keywords": [],
"author": "Name",
"license": "MIT",
"bugs": {
"url": "https://github.com/Simple/Project/issues"
},
"homepage": "https://github.com/Simple/Project#readme",
"devDependencies": {
"babel-core": "^6.26.0",
"babel-loader": "^7.1.2",
"babel-preset-env": "^1.6.1",
"css-loader": "^0.28.7",
"extract-text-webpack-plugin": "^3.0.2",
"file-loader": "^1.1.5",
"ng-annotate-loader": "^0.6.1",
"node-sass": "^4.6.1",
"normalize.css": "^7.0.0",
"sass-loader": "^6.0.6",
"style-loader": "^0.19.0",
"url-loader": "^0.6.2"
},
"dependencies": {
"angular": "^1.6.6",
"angular-animate": "^1.6.6",
"angular-resource": "^1.6.6",
"angular-route": "^1.6.6",
"angular-ui-bootstrap": "^2.5.6",
"ejs": "^2.5.7",
"express": "^4.16.2",
"jquery": "^3.2.1",
"webpack": "^3.8.1"
},
"engines": {
"node": "^8.9.1",
"yarn": "^1.3.2"
}}
I've set Webpack to put all .js, vendor files, and styles into /dist which is .gitignore(d) in my git, but NOT in my push to Heroku. You can check out my git here:
https://github.com/SalamanderMike/portfolio
I've been researching this for a couple days and the answer hasn't revealed itself. I'm hoping someone can help me figure it out. I'm sure it's a simple thing I am overlooking. Thanks for your help!