deepseek-ai/deepseek-harness · error · MaterializeError

functions are not plain JSON data

Error message

functions are not plain JSON data

What it means

Error "functions are not plain JSON data" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/workflow/workflow-worker-thread/src/realm.ts:90

    // A property read ran script code that threw; total-ize it so callers can
    // keep the narrow MaterializeError contract.
    throw new MaterializeError(root, `reading the value threw: ${renderThrown(error)}`)
  }
}

function materialize(value: unknown, path: string, seen: Set<object>): unknown {
  switch (typeof value) {
    case 'boolean':
    case 'string':
      return value
    case 'number': {
      if (!Number.isFinite(value)) throw new MaterializeError(path, 'non-finite numbers are not JSON data')
      return value
    }
    case 'bigint':
      throw new MaterializeError(path, 'bigints are not JSON data')
    case 'function':
      throw new MaterializeError(path, 'functions are not plain JSON data')
    case 'symbol':
      throw new MaterializeError(path, 'symbols are not plain JSON data')
    case 'undefined':
      throw new MaterializeError(path, 'undefined is not JSON data')
    case 'object':
      break
  }
  if (value === null) return null
  const objectValue: object = value
  if (seen.has(objectValue)) throw new MaterializeError(path, 'circular references are not JSON data')
  seen.add(objectValue)
  try {
    if (Array.isArray(objectValue)) return materializeArray(objectValue, path, seen)
    return materializeObject(objectValue, path, seen)
  } finally {
    seen.delete(objectValue)
  }
}

View on GitHub (pinned to b150a551b8)

Solutions

1. Strip functions from the returned value; return only plain JSON data.

When it happens

Trigger: Thrown at packages/workflow/workflow-worker-thread/src/realm.ts:90 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of deepseek-ai/deepseek-harness@b150a551b8 (2026-08-24). Data as JSON: /api/errors/e806c2fe3c3a0f48. Report an issue: GitHub.