Separate native module and permission failures

Understand the likely causes

• Specification, Codegen artifacts, native implementation, registration, framework integration, permission, and hardware support are independent boundaries.
• A fake reader bypasses the native layer, and a JavaScript refresh may not apply changed native build inputs. Unknown or unavailable results can also be incorrectly converted to a real zero measurement.

Identify the exact target and first failure

Capture the selected React Native/framework versions, target, native dependency versions, build variant, module name, and first relevant exception. Classify whether the failure is lookup absence, generated integration, malformed result, denied permission, or unsupported capability. A JavaScript type declaration cannot establish native registration. Do not begin with broad cleanup that changes the environment before preserving a minimal reproduction. Keep diagnostics synthetic and omit credentials or signing material. This read-only classification does not require creating a device, requesting access, or modifying a real account.

Compare the declared protocol and actual integration

Check exact module names, supported specification types, method names, units, nullability, and error categories against the compatible native implementation. TurboModuleRegistry.get can expose optional absence, while getEnforcing throws when an expected module is unavailable. Neither supplies a missing implementation. Codegen requires its documented project integration, and native configuration changes can need an actual rebuild in the authorized host. Do not change an arbitrary name merely to suppress the message. Verify framework and target support before assuming a module working on one platform also exists on another.

Preserve absence, zero, and invalid payload separately

The program demonstrates the application mapping for a percentage result. Unavailable is not zero, and an out-of-range value is a protocol error rather than a default reading. Keep this model behind an injected adapter so tests can choose these cases without native access. A passing mapping test cannot validate Codegen, thread ownership, manifest or entitlement configuration, or actual permissions. Known native failures should map to documented application outcomes, while unexpected defects retain safe diagnostic context. Do not log complete private payloads merely because a generic error object contains them.

function percentageLabel(value) {
  if (value === null) return 'Unavailable';
  if (!Number.isSafeInteger(value) || value < 0 || value > 100) {
    throw new Error('INVALID_PERCENT');
  }
  return String(value) + '%';
}
console.log(percentageLabel(null));
console.log(percentageLabel(0));
try { percentageLabel(101); }
catch (error) { console.log(error.message); }

Unavailable
0%
INVALID_PERCENT

Verify permission and capability after registration

Request permission only in a comprehensible feature action and keep status refresh separate from consent. Preserve documented denial categories and platform qualifiers; PermissionsAndroid is not an iOS permission API. On activation, reconcile changed settings without automatically repeating the prior command. After a repair, use the authorized target workflow to test successful access, denial, unavailable capability, removal during pending work, and recovery. A fake test remains useful for application policy but cannot replace those target checks. No build, permission request, account, generated native artifact, or device operation is executed by this guide.

Keep it from recurring

• Keep a target capability matrix, narrow adapters, and stable protocol fixtures. Retain explicit host assumptions and verify native changes through the selected documented workflow.