different-ai/openwork · error · InterpreterRuntimeError

Array.from expects an array, string, Map, Set, or…

Error message

Array.from expects an array, string, Map, Set, or array-like value.

What it means

When Array.from is called with a single argument, invokeArrayStatic validates the source: it accepts arrays, strings, Map, Set, or any object with a numeric length property. Anything else (plain objects without length, numbers, null, undefined) throws this error because the sandbox cannot safely iterate the value.

Solutions

Pass an array, string, Map, Set, or object with a numeric length property
For plain objects use Object.entries(obj) or Object.keys(obj) first (check Object method support)
Guard the input for null/undefined before calling Array.from

Example fix

// before
const arr = Array.from(obj);
// after
const arr = Array.from(Object.entries(obj));

Defensive patterns

Strategy: validation

Validate before calling

function isArrayFromSourceSafe(v) {
  return Array.isArray(v) || typeof v === 'string' || v instanceof Map || v instanceof Set ||
    (v !== null && typeof v === 'object' && typeof v.length === 'number');
}

Type guard

function isArrayLike(v) { return v !== null && typeof v === 'object' && typeof v.length === 'number'; }

Prevention

Guard inputs for null/undefined before Array.from
Use Object.entries/Object.keys for plain objects
Only pass arrays, strings, Maps, Sets, or length-bearing objects

When it happens

Trigger: Array.from(<unsupported value>) with one argument where the value is e.g. a plain object like {a:1}, a number, null/undefined, or a non-array-like custom object lacking a numeric length.

Common situations: Assuming Array.from converts object key/value pairs (it needs Object.entries first); passing a Map and expecting entries (supported here, but yields [key,value] pairs); defensive code passing possibly-null values into Array.from.

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

AI-assisted analysis of different-ai/openwork@2b7df46e8a (2026-09-01). Data as JSON: /api/errors/83be134046eb006e. Report an issue: GitHub.

Appendix: source

Thrown at packages/codemode/src/interpreter/runtime.ts:544

      }
      // Map/Set materialize directly (the data checkpoint would serialize them to {}).
      if (args[0] instanceof SandboxMap)
        return Array.from((args[0] as SandboxMap).map.entries(), ([key, item]) => [key, item])
      if (args[0] instanceof SandboxSet) return Array.from((args[0] as SandboxSet).set.values())
      if (args[0] instanceof SandboxURLSearchParams) {
        return Array.from(args[0].params.entries(), ([key, value]) => [key, value])
      }
      const source = boundedData(args[0], "Array.from input")
      if (typeof source === "string") return Array.from(source)
      if (Array.isArray(source)) return [...source]
      if (
        source !== null &&
        typeof source === "object" &&
        typeof (source as { length?: unknown }).length === "number"
      ) {
        return Array.from(source as ArrayLike<unknown>)
      }
      throw new InterpreterRuntimeError("Array.from expects an array, string, Map, Set, or array-like value.", node)
    }
    default:
      throw new InterpreterRuntimeError(`Array.${name} is not available in CodeMode.`, node)
  }
}

const invokeGlobalMethod = (ref: GlobalMethodReference, args: Array<unknown>, node: AstNode): unknown => {
  if (ref.namespace === "console")
    throw new InterpreterRuntimeError(`console.${ref.name} is not available in CodeMode.`, node)
  if (ref.namespace === "Object") return invokeObjectMethod(ref.name, args, node)
  if (ref.namespace === "Math") return invokeMathMethod(ref.name, args, node)
  if (ref.namespace === "Array") return invokeArrayStatic(ref.name, args, node)
  if (ref.namespace === "Number") return invokeNumberStatic(ref.name, args, node)
  if (ref.namespace === "String") return invokeStringStatic(ref.name, args, node)
  if (ref.namespace === "URL") return invokeURLStatic(ref.name, args, node)
  if (ref.namespace === "Date") {
    if (!dateStatics.has(ref.name))
      throw new InterpreterRuntimeError(`Date.${ref.name} is not available in CodeMode.`, node)

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