Fix an error when querying multipolygons in dynamic mode

GitOrigin-RevId: 725a5501699c06356b07a79538697df8fd67d5b9

Author: mourner

src/source/geojson_rt.ts

@@ -333,7 +333,7 @@ function transformAndClipPolygon(input: number[], z2: number, tx: number, ty: nu
         Math.round(EXTENT * (clipped[i] * z2 - tx)),
         Math.round(EXTENT * (clipped[i + 1] * z2 - ty))
     ]);
-    out.push(ring);
+    if (ring.length) out.push(ring);
 }
 
 // rewind a polygon ring to a given winding order (clockwise or anti-clockwise)

src/source/vector_tile_to_pbf.ts

@@ -113,6 +113,7 @@ function writeGeometry(feature: Feature, pbf: Pbf) {
 
     } else {
         for (const ring of geometry) {
+            if (ring.length === 0) continue;
             pbf.writeVarint(command(1, 1));
             const lineCount = ring.length - (type === 3 ? 1 : 0); // do not write polygon closing path as lineto
             for (let i = 0; i < lineCount; i++) {

test/unit/source/vector_tile_to_pbf.test.ts

@@ -1,5 +1,7 @@
 import {test, expect} from '../../util/vitest';
 import writePbf from '../../../src/source/vector_tile_to_pbf';
+import Pbf from 'pbf';
+import {VectorTile} from '@mapbox/vector-tile';
 
 import type {Feature} from '../../../src/source/geojson_wrapper';
 
@@ -25,3 +27,18 @@ test('loadData does not error on non-numeric feature IDs', () => {
         writePbf({test: features});
     }).not.toThrowError();
 });
+
+test('does not encode empty rings', () => {
+    const features: Feature[] = [{
+        id: 1,
+        type: 2,
+        tags: {},
+        geometry: [[[0, 0]], []]
+    }];
+
+    expect(() => {
+        const buf = writePbf({test: features});
+        const tile = new VectorTile(new Pbf(buf));
+        tile.layers.test.feature(0).loadGeometry();
+    }).not.toThrowError();
+});