different-ai/openwork · error · InterpreterRuntimeError

Object.fromEntries expects an array of [key, value] pairs.

Error message

Object.fromEntries expects an array of [key, value] pairs.

What it means

Object.fromEntries in CodeMode requires its argument to be an array of [key, value] pairs (or a SandboxURLSearchParams). If the top-level argument is not an array, invokeObjectMethod throws this message before inspecting individual pairs.

Source

Thrown at packages/codemode/src/stdlib/object.ts:64

        }
        for (const [key, item] of Object.entries(value)) guardedSet(out, key, item)
      }
      return out
    }
    case "fromEntries": {
      if (args[0] instanceof SandboxMap) {
        const out: Record<string, unknown> = Object.create(null)
        for (const [key, item] of args[0].map.entries()) guardedSet(out, coerceToString(key), item)
        return out
      }
      if (args[0] instanceof SandboxURLSearchParams) {
        const out: Record<string, unknown> = Object.create(null)
        for (const [key, value] of args[0].params.entries()) guardedSet(out, key, value)
        return out
      }
      const pairs = boundedData(args[0], "Object.fromEntries input")
      if (!Array.isArray(pairs)) {
        throw new InterpreterRuntimeError("Object.fromEntries expects an array of [key, value] pairs.", node)
      }
      const out: Record<string, unknown> = Object.create(null)
      for (const pair of pairs) {
        if (!Array.isArray(pair)) {
          throw new InterpreterRuntimeError("Object.fromEntries expects [key, value] pairs.", node)
        }
        guardedSet(out, String(pair[0]), pair[1])
      }
      return out
    }
  }
  throw new InterpreterRuntimeError(`Object.${name} is not available in CodeMode.`, node)
}

View on GitHub (pinned to 2b7df46e8a)

Solutions

1. Pass an array of pairs: Object.fromEntries(Object.entries(obj)) when converting an object
2. Parse JSON strings first: Object.fromEntries(JSON.parse(serializedPairs))
3. Default the argument: Object.fromEntries(pairs ?? [])
4. If you have a Map-like sandbox value, use its .entries()/params API as the branch supports URLSearchParams-style inputs

Example fix

// before
const record = Object.fromEntries(myMapLike)
// after
const record = Object.fromEntries(Object.entries(myMapLike))

function assertPairs(v: unknown): asserts v is Array<Array<unknown>> {
  if (!Array.isArray(v)) throw new Error('Object.fromEntries needs an array of pairs')
}
const pairs = raw ?? []

const isPairArray = (v: unknown): v is Array<[string, unknown]> =>
  Array.isArray(v) && v.every((p) => Array.isArray(p))

try {
  return Object.fromEntries(input)
} catch (e) {
  if (e instanceof InterpreterRuntimeError && e.message.includes('expects an array of [key, value] pairs')) {
    return Object.fromEntries(Object.entries(input as Record<string, unknown>))
  }
  throw e
}

When it happens

Trigger: Object.fromEntries({a:1}) (object instead of array), Object.fromEntries(map) using a plain object where a Map was intended, Object.fromEntries(null/undefined), Object.fromEntries(entriesString) where a serialized JSON string was never parsed.

Common situations: Converting a Map-like object to a record without calling .entries() first; receiving Object.entries-style arrays as JSON strings from an API; passing undefined when the upstream variable failed to populate.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• Object.${name} expects a data object.
• Object.keys expects a data object or array.
• Object.assign expects data objects.
• Object.fromEntries expects [key, value] pairs.
• String.${name} expects argument ${index + 1} to be a number.

AI-assisted analysis of different-ai/openwork@2b7df46e8a (2026-09-01). Data as JSON: /api/errors/2d4b6f87e6eec260. Report an issue: GitHub.