Mystery error on gatsby build

Site: (branch deploy)
Deploy log: Netlify App

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" ERROR #85928

An error occurred during parallel query running.
Go here for troubleshooting tips: Parallel Query Running · gatsbyjs/gatsby · Discussion #32389 · GitHub

Error: Worker exited before finishing task"

I had an accidental reference loop in my sanity schema! (like a project was referencing and institution that was referencing a project …)

thanks for coming back and marking your solution.