@bencstrs Same questions to you then 
Can you check ghost doctor and also take a look at your current/node_modules folder and see if sharp is in there?
Sure, here is the ghost doctor output:
✔ Checking system Node.js version
✔ Checking logged in user
✔ Ensuring user is not logged in as ghost user
✔ Checking if logged in user is directory owner
✔ Checking current folder permissions
✔ Checking operating system compatibility
✔ Checking for a MySQL installation
+ sudo systemctl is-active ghost_example-com
Instance is currently running
ℹ Validating config [skipped]
✔ Checking folder permissions
✔ Checking file permissions
✔ Checking content folder ownership
✔ Checking memory availability
I checked node_modules and I do see a sharp folder in there.
FYI - I added some more notes to the GitHub issue. It does seem to be an issue with the sharp package.