Build on Vercel fails

[abrichr]

Forking this repo and attempting to deploy the fork to Vercel with defaults results in the following error:

[23:10:21.336] Cloning github.com/abrichr/rvubot.com (Branch: master, Commit: 2b987b9)
[23:10:21.945] Cloning completed: 608.372ms
[23:10:22.232] Looking up build cache...
[23:10:22.365] Build Cache not found
[23:10:22.414] Running "vercel build"
[23:10:23.054] Vercel CLI 28.4.12-5b68066
[23:10:23.463] Installing dependencies...
[23:10:23.888] yarn install v1.22.17
[23:10:23.967] [1/4] Resolving packages...
[23:10:24.299] [2/4] Fetching packages...
[23:10:39.563] [3/4] Linking dependencies...
[23:10:39.566] warning " > @next-auth/[email protected]" has incorrect peer dependency "next-auth@>=4".
[23:10:39.568] warning "next > styled-jsx > @babel/[email protected]" has unmet peer dependency "@babel/core@^7.0.0-0".
[23:10:39.571] warning " > [email protected]" has unmet peer dependency "@types/node@*".
[23:10:46.241] [4/4] Building fresh packages...
[23:10:53.041] $ prisma generate || true
[23:10:54.531] Prisma schema loaded from prisma/schema.prisma
[23:10:56.489] 
[23:10:56.489] ✔ Generated Prisma Client (3.0.2) to ./node_modules/@prisma/client in 221ms
[23:10:56.489] You can now start using Prisma Client in your code. Reference: https://pris.ly/d/client
[23:10:56.490] ```
[23:10:56.490] import { PrismaClient } from '@prisma/client'
[23:10:56.490] const prisma = new PrismaClient()
[23:10:56.490] ```
[23:10:56.572] Done in 32.69s.
[23:10:56.609] Detected Next.js version: 11.1.2
[23:10:56.612] Running "yarn run build"
[23:10:56.981] yarn run v1.22.17
[23:10:57.022] $ next build
[23:10:58.016] info  - Using webpack 5. Reason: Enabled by default https://nextjs.org/docs/messages/webpack5
[23:10:58.780] Attention: Next.js now collects completely anonymous telemetry regarding usage.
[23:10:58.781] This information is used to shape Next.js' roadmap and prioritize features.
[23:10:58.781] You can learn more, including how to opt-out if you'd not like to participate in this anonymous program, by visiting the following URL:
[23:10:58.781] https://nextjs.org/telemetry
[23:10:58.781] 
[23:10:58.881] Browserslist: caniuse-lite is outdated. Please run:
[23:10:58.882] npx browserslist@latest --update-db
[23:10:58.882] 
[23:10:58.882] Why you should do it regularly:
[23:10:58.882] https://github.com/browserslist/browserslist#browsers-data-updating
[23:10:58.915] info  - Checking validity of types...
[23:11:05.808] Failed to compile.
[23:11:05.808] 
[23:11:05.808] ./pages/api/auth/[...nextauth].ts:14:7
[23:11:05.809] Type error: Type 'string | undefined' is not assignable to type 'string'.
[23:11:05.809]   Type 'undefined' is not assignable to type 'string'.
[23:11:05.809] 
[23:11:05.809] �[0m �[90m 12 | �[39m  providers�[33m:�[39m [�[0m
[23:11:05.809] �[0m �[90m 13 | �[39m    �[33mFacebookProvider�[39m({�[0m
[23:11:05.810] �[0m�[31m�[1m>�[22m�[39m�[90m 14 | �[39m      clientId�[33m:�[39m process�[33m.�[39menv�[33m.�[39m�[33mFACEBOOK_ID�[39m�[33m,�[39m�[0m
[23:11:05.810] �[0m �[90m    | �[39m      �[31m�[1m^�[22m�[39m�[0m
[23:11:05.810] �[0m �[90m 15 | �[39m      clientSecret�[33m:�[39m process�[33m.�[39menv�[33m.�[39m�[33mFACEBOOK_SECRET�[39m�[33m,�[39m�[0m
[23:11:05.810] �[0m �[90m 16 | �[39m    })�[33m,�[39m�[0m
[23:11:05.810] �[0m �[90m 17 | �[39m    �[33mGitHubProvider�[39m({�[0m
[23:11:05.855] error Command failed with exit code 1.
[23:11:05.857] info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
[23:11:05.879] Error: Command "yarn run build" exited with 1

More readable mangled portion:

23:11:05.809 | 12 \|   providers: [
23:11:05.809 | 13 \|     FacebookProvider({
23:11:05.810 | > 14 \|       clientId: process.env.FACEBOOK_ID,
23:11:05.810 | \|       ^
23:11:05.810 | 15 \|       clientSecret: process.env.FACEBOOK_SECRET,
23:11:05.810 | 16 \|     }),
23:11:05.810 | 17 \|     GitHubProvider({