Function extractNestedErrorMessage

src/services/api/errorUtils.ts:169–198

* Extract a human-readable message from a deserialized API error that lacks * a top-level `.message`. * * Checks two nesting levels (deeper first for specificity): * 1. `error.error.error.message` — standard Anthropic API shape * 2. `error.error.message` — Bedrock shape

(error: APIError)

 * 2. `error.error.message` — Bedrock shape
 */
function extractNestedErrorMessage(error: APIError): string | null {
  if (!hasNestedError(error)) {
    return null
  }

  // Access `.error` via the narrowed type so TypeScript sees the nested shape
  // instead of the SDK's `Object | undefined`.
  const narrowed: NestedAPIError = error
  const nested = narrowed.error

  // Standard Anthropic API shape: { error: { error: { message } } }
  const deepMsg = nested?.error?.message
  if (typeof deepMsg === 'string' && deepMsg.length > 0) {
    const sanitized = sanitizeMessageHTML(deepMsg)
    if (sanitized.length > 0) {
      return sanitized
    }
  }

  // Bedrock shape: { error: { message } }
  const msg = nested?.message
  if (typeof msg === 'string' && msg.length > 0) {
    const sanitized = sanitizeMessageHTML(msg)
    if (sanitized.length > 0) {
      return sanitized
    }
  }

  return null
}

export function formatAPIError(error: APIError): string {
  // Extract connection error details from the cause chain