different-ai/openwork · error · InterpreterRuntimeError

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

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.

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)

View on GitHub (pinned to 2b7df46e8a)

Solutions

1. Pass an array, string, Map, Set, or object with a numeric length property
2. For plain objects use Object.entries(obj) or Object.keys(obj) first (check Object method support)
3. 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));

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');
}

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

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

• Array.from(...) does not support a map function in CodeMode;
• String.${name} expects argument ${index + 1} to be a number.
• String.repeat expects a finite non-negative count.
• String method '${name}' is not available in CodeMode.
• Array.${name} is not available in CodeMode.

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