chore: add an error log when adapter is missing (#994)

## Description

This PR introduces more discoverability to a potential common pitfall of
user not calling initExecutorch, before using the resource fetcher.

### Introduces a breaking change?

- [ ] Yes
- [x] No

### Type of change

- [ ] Bug fix (change which fixes an issue)
- [ ] New feature (change which adds functionality)
- [ ] Documentation update (improves or adds clarity to existing
documentation)
- [x] Other (chores, tests, code style improvements etc.)

### Tested on

- [ ] iOS
- [ ] Android

### Testing instructions

<!-- Provide step-by-step instructions on how to test your changes.
Include setup details if necessary. -->

### Screenshots

<!-- Add screenshots here, if applicable -->

### Related issues

<!-- Link related issues here using #issue-number -->

### Checklist

- [ ] I have performed a self-review of my code
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] I have updated the documentation accordingly
- [ ] My changes generate no new warnings

### Additional notes

<!-- Include any additional information, assumptions, or context that
reviewers might need to understand this PR. -->

Author: chmjkb

packages/react-native-executorch/src/utils/ResourceFetcher.ts

@@ -32,6 +32,7 @@ import { ResourceSource } from '../types/common';
 import { RnExecutorchError } from '../errors/errorUtils';
 import { RnExecutorchErrorCode } from '../errors/ErrorCodes';
 import { ResourceFetcherUtils } from './ResourceFetcherUtils';
+import { Logger } from '../common/Logger';
 
 /**
  * Adapter interface for resource fetching operations.
@@ -104,9 +105,13 @@ export class ResourceFetcher {
    */
   static getAdapter(): ResourceFetcherAdapter {
     if (!this.adapter) {
+      const errorMessage =
+        'ResourceFetcher adapter is not initialized. Please call initExecutorch({ resourceFetcher: ... }) with a valid adapter, e.g., from react-native-executorch-expo-resource-fetcher or react-native-executorch-bare-resource-fetcher. For more details please refer: https://docs.swmansion.com/react-native-executorch/docs/next/fundamentals/loading-models';
+      // for sanity :)
+      Logger.error(errorMessage);
       throw new RnExecutorchError(
         RnExecutorchErrorCode.ResourceFetcherAdapterNotInitialized,
-        'ResourceFetcher adapter is not initialized. Please call initExecutorch({ resourceFetcher: ... }) with a valid adapter, e.g., from react-native-executorch-expo-resource-fetcher or react-native-executorch-bare-resource-fetcher. For more details please refer: https://docs.swmansion.com/react-native-executorch/docs/next/fundamentals/loading-models'
+        errorMessage
       );
     }
     return this.adapter;