Hugo site fails to deploy to Firebase via GitHub/Cloud Build

## Affected builder image

gcr.io/cloud-builders-community/firebase

## Expected Behavior

Site to deploy on git commit/push

## Actual Behavior

Hugo part of command runs no problem, and then this...

Pulling image: gcr.io/wrightway-design-store-268123/firebase
Using default tag: latest
latest: Pulling from wrightway-design-store-268123/firebase
3192219afd04: Already exists
17c160265e75: Already exists
cc4fe40d0e61: Already exists
9d647f502a07: Already exists
c8bd59397b26: Already exists
f9289dfd19be: Already exists
9553b08b6292: Pulling fs layer
37581b1ce15a: Pulling fs layer
45ea08f1ad05: Pulling fs layer
ff404c5c3ea2: Pulling fs layer
9bc8ef53581e: Pulling fs layer
edad2a933ba9: Pulling fs layer
ff404c5c3ea2: Waiting
edad2a933ba9: Waiting
9bc8ef53581e: Waiting
45ea08f1ad05: Verifying Checksum
45ea08f1ad05: Download complete
37581b1ce15a: Verifying Checksum
37581b1ce15a: Download complete
9bc8ef53581e: Verifying Checksum
9bc8ef53581e: Download complete
edad2a933ba9: Verifying Checksum
edad2a933ba9: Download complete
9553b08b6292: Verifying Checksum
9553b08b6292: Download complete
ff404c5c3ea2: Verifying Checksum
ff404c5c3ea2: Download complete
9553b08b6292: Pull complete
37581b1ce15a: Pull complete
45ea08f1ad05: Pull complete
ff404c5c3ea2: Pull complete
9bc8ef53581e: Pull complete
edad2a933ba9: Pull complete
Digest: sha256:61751f971e690dc513d9220f5a52b87ef923af2bd9d85a86e75c3a79b2f2fd8a
Status: Downloaded newer image for gcr.io/wrightway-design-store-268123/firebase:latest
gcr.io/wrightway-design-store-268123/firebase:latest
standard_init_linux.go:211: exec user process caused "no such file or directory"

## Steps to Reproduce the Problem

1. Clone repo https://github.com/adampwright/design-store.git
2. Create trigger - push
3. Git commit...etc

## Additional Info

Deploys fine direct to Firebase using "hugo && firebase deploy" but not with CloudBuild/GitHub.