Troubleshooting AvMapsLoader: Common Errors and FixesAvMapsLoader is a useful library for loading map data and assets in applications, but like any complex component it can produce a range of errors depending on environment, configuration, or data quality. This article walks through the most common problems developers encounter with AvMapsLoader, explains why they happen, and provides concrete fixes and debugging techniques.
1) Initialization fails or loader doesn’t start
Symptoms
- The loader never emits a ready or progress event.
- Console shows no network activity related to map tiles or assets.
- Application appears to hang at map initialization.
Common causes
- Incorrect import or package version mismatch.
- Missing or wrong initialization options (API key, base path, resource manifest).
- Loader instance created before the platform or DOM is ready.
- Silent errors swallowed by try/catch or promise chains.
Fixes
- Verify correct package and version: ensure package.json lists the AvMapsLoader version you expect and rebuild node_modules (npm ci or yarn install).
- Check import paths; use the documented entry point for your environment (ESM/CJS/browser bundle).
- Provide required options (API key, base URLs, or local manifest). Example:
import AvMapsLoader from 'avmapsloader'; const loader = new AvMapsLoader({ apiKey: 'YOUR_KEY', manifestUrl: '/maps/manifest.json' }); loader.start(); - Wait for DOM or platform readiness:
window.addEventListener('DOMContentLoaded', () => loader.start()); - Remove broad try/catch blocks while debugging so errors surface in console.
2) Network errors, 404s, or CORS failures when fetching tiles/assets
Symptoms
- 404 responses for tile or asset URLs.
- Browser blocks requests with CORS errors.
- Intermittent tile loading or missing icons/labels.
Common causes
- Incorrect tile URL template or base path.
- Manifest references wrong filenames or folder structure.
- Server not configured for CORS or missing proper headers.
- Using local files via file:// protocol in the browser.
Fixes
- Inspect network requests in DevTools to see exact failing URL and adjust the loader’s basePath or URL template.
- Ensure server hosts the tile/asset paths exactly as the manifest expects. If your manifest uses relative paths, confirm the loader’s base URL matches.
- Enable CORS on server responses. Typical header: Access-Control-Allow-Origin: * For credentials, set appropriate Access-Control-Allow-Credentials and set withCredentials on requests if needed.
- Serve map assets over HTTP(S) during development (use a simple static server instead of file://).
- If using a CDN, verify cache or rewrite rules aren’t removing expected files.
3) Tile seams, missing tiles, or visual artifacts
Symptoms
- Visible seams between tiles at certain zoom levels.
- Blank regions where tiles should appear.
- Flickering or incorrect tiles when panning/zooming.
Common causes
- Tile coordinate mismatch (TMS vs XYZ), wrong origin or y-axis flipping.
- Wrong tile size, tile buffer, or pixel ratio settings.
- Race conditions where multiple tile layers overlap during updates.
- Corrupt tile data or mismatched projection settings.
Fixes
- Confirm the tile scheme: if server uses TMS (origin bottom-left) but loader expects XYZ (origin top-left), enable appropriate y-flip option or convert coordinates.
- Ensure tileSize in loader options matches server tile size (commonly 256 or 512).
- If supporting high-DPI displays, set devicePixelRatio handling and request correct tile scale (@2x tiles) or downscale appropriately.
- Throttle tile requests during rapid zoom/pan to avoid race conditions; most loaders provide a request queue or abort previous requests.
- Verify map projection (EPSG:3857 vs EPSG:4326). Ensure both server tiles and loader use the same projection.
4) Slow performance or memory leaks
Symptoms
- App slows down after prolonged use; frame drops during panning/zooming.
- Memory usage steadily increases until the browser becomes unresponsive.
- Tile cache grows indefinitely.
Common causes
- Loader retains references to tiles or feature objects; weak cleanup.
- Tile cache settings too large or disabled eviction policy.
- Excessive vector feature rendering or heavy post-processing (shaders, filters).
- Event listeners or intervals not removed on unload.
Fixes
- Enable or configure tile cache eviction (max tiles, LRU policy). Example:
const loader = new AvMapsLoader({ tileCacheSize: 500 }); - Explicitly call loader.destroy() or loader.clear() when the map component unmounts.
- Remove event listeners and cancel animation frames or intervals:
loader.off('tileloaded', onTileLoaded); cancelAnimationFrame(myAnimId); - Simplify vector rendering: reduce vertex counts, use tile-level clipping, or aggregate features.
- Profile memory in Chrome DevTools (Heap snapshots) to find retained objects and where they’re referenced.
5) Intermittent failures in mobile or low-bandwidth environments
Symptoms
- Tiles fail to load on mobile data but work on Wi‑Fi.
- Timeouts or aborted requests on flaky networks.
- Excessive retries or duplicate requests consume bandwidth.
Common causes
- Aggressive timeouts or no retry backoff strategy.
- Large initial payloads (big manifests, high-res tiles) that time out on slow connections.
- Not using efficient compression (Gzip/Brotli) or HTTP/2 multiplexing.
Fixes
- Implement exponential backoff and limited retries for failed requests.
- Split large manifests into smaller files or lazy-load resources for initial view only.
- Serve compressed assets and enable HTTP/2 on servers.
- Provide lower-resolution or vector tile fallbacks for constrained devices.
- Detect network conditions via Network Information API and reduce concurrency or quality accordingly.
6) Authentication and authorization errors
Symptoms
- ⁄403 HTTP responses when fetching tiles or APIs.
- Loader reports invalid token or unauthorized access.
Common causes
- Expired or missing API key or token.
- Token not attached to requests due to CORS preflight or credential settings.
- Server expects signed URLs or HMAC that the client doesn’t provide.
Fixes
- Verify API key validity and server clocks (for time-limited tokens).
- Ensure authentication headers or query parameters are actually sent. For browser requests, ensure CORS policy allows Authorization header and server includes Access-Control-Allow-Headers: Authorization.
- If using signed URLs, generate them server-side and return to client; avoid embedding secret keys in client code.
- Log full request headers during debugging to confirm credentials are present.
7) Data parsing errors or unexpected feature rendering
Symptoms
- JSON or binary parsing exceptions.
- Features appear at wrong coordinates or with malformed properties.
- Error messages about unsupported formats.
Common causes
- Mismatched data format (e.g., expecting MVT but receiving GeoJSON).
- Corrupted downloads or incomplete responses.
- Wrong decoder configuration (wrong endian, protobuf schema mismatch).
Fixes
- Verify content-type and inspect a failing payload in DevTools.
- Ensure loader is configured to decode the correct format (MVT, GeoJSON, TopoJSON).
- Add checksum or content-length validation to detect truncated downloads.
- Update or align decoder libraries with the tile producer’s version.
8) Integration issues with frameworks (React, Angular, Vue)
Symptoms
- Map re-renders cause duplicated tiles or multiple loaders.
- Memory or event leaks when components mount/unmount.
- State-driven updates conflict with loader’s internal lifecycle.
Common causes
- Creating loader inside render() or template without proper memoization.
- Not cleaning up loader on component unmount.
- Two-way binding causes repeated initialization.
Fixes
- Initialize loader in lifecycle hooks (useEffect with empty deps in React, mounted in Vue, ngOnInit in Angular) and destroy in cleanup hooks (useEffect return, beforeDestroy). Example (React):
useEffect(() => { const loader = new AvMapsLoader(opts); loader.start(); return () => loader.destroy(); }, []); - Keep loader instance in a ref or service so re-renders don’t recreate it.
- Use stable keys/IDs for map container elements to avoid framework remounts.
9) Errors during build or bundling
Symptoms
- Build fails with module not found, polyfill, or syntax errors.
- The loader works in dev but breaks in production bundle.
Common causes
- Library ships multiple builds (ESM, CJS, UMD) and bundler resolves wrong entry.
- Missing polyfills for Node APIs used in browser builds (fs, path).
- Tree-shaking removes required side-effectful modules.
Fixes
- Configure bundler to prefer the correct module field (main/module/browser) or add an alias to the UMD bundle if needed.
- Replace or polyfill Node-specific modules; use bundler plugins to stub them out.
- Mark necessary modules as side-effectful in package.json or bundler config to avoid stripping.
- Test production build locally with a static server identical to deployment.
10) Helpful debugging checklist and tools
Quick checklist
- Check console and network panel for exact errors and failing URLs.
- Confirm loader configuration (basePath, tileSize, scheme, manifest).
- Validate server CORS and response headers.
- Test with a minimal reproducible example.
- Use profiler and heap snapshots for performance issues.
- Ensure proper lifecycle management in frameworks.
Useful tools
- Browser DevTools (Network, Console, Performance, Memory).
- curl or Postman to inspect server responses and headers.
- Tile inspectors (e.g., mapbox tilejson tools) to validate tile endpoints and metadata.
- Heap snapshot tools and Lighthouse for performance audits.
Conclusion
Most AvMapsLoader problems stem from configuration mismatches, network/server issues, or lifecycle management in applications. Systematic debugging—checking network requests, validating formats, and ensuring proper initialization/cleanup—will resolve the majority of issues. When stuck, reproduce the problem in a minimal example and incrementally reintroduce complexity to find the root cause.
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