improve range check in VectorTileLayer#getFeature

Author: pirxpilot

lib/vectortilelayer.js

@@ -21,11 +21,10 @@ export class VectorTileLayer {
 
   // return feature `i` from this layer as a `VectorTileFeature`
   feature(i) {
-    if (i < 0 || i >= this._features.length) throw new Error('feature index out of bounds');
-
-    this._pbf.pos = this._features[i];
-
-    const end = this._pbf.readVarint() + this._pbf.pos;
+    const pos = this._features[i];
+    if (pos == null) throw new RangeError(`feature index ${i} out of bounds`);
+    this._pbf.pos = pos;
+    const end = this._pbf.readVarint() + pos;
     return new VectorTileFeature(this._pbf, end, this.extent, this._keys, this._values);
   }
 }