Fix crash when a symbol layer without feature-state paint gets a pain…

src/source/tile.ts

@@ -797,8 +797,9 @@ class Tile {
             const imagePositions: SpritePositions = this.imageAtlas ? Object.fromEntries(this.imageAtlas.patternPositions) : {};
             const withStateUpdates = Object.keys(sourceLayerStates).length > 0 && !isBrightnessChanged;
             bucket.hasAppearances = bucket.layers.some(layer => layer.appearances && layer.appearances.length > 0);
-            const layers = withStateUpdates ? bucket.stateDependentLayers : bucket.layers;
-            if ((withStateUpdates && bucket.stateDependentLayers.length !== 0) || isBrightnessChanged || hasPaintUpdate || needsSymbolUBOUpdate) {
+            const hasStateDependentLayers = withStateUpdates && bucket.stateDependentLayers.length !== 0;
+            const layers = hasStateDependentLayers ? bucket.stateDependentLayers : bucket.layers;
+            if (hasStateDependentLayers || isBrightnessChanged || hasPaintUpdate || needsSymbolUBOUpdate) {
                 const vtLayers = this.latestFeatureIndex.loadVTLayers();
                 const sourceLayer = vtLayers[sourceLayerId];
                 bucket.update(sourceLayerStates, sourceLayer, images, imagePositions, layers, isBrightnessChanged, brightness, this.tileID.canonical);
@@ -849,15 +850,14 @@ class Tile {
                     }
                 }
             }
-            if ((withStateUpdates && bucket.stateDependentLayers.length !== 0) || isBrightnessChanged || bucket.hasAppearances) {
+            if (hasStateDependentLayers || isBrightnessChanged || bucket.hasAppearances) {
                 const globalProperties = {
                     zoom: painter.transform.zoom,
                     pitch: painter.transform.pitch,
                     brightness: painter.style.getBrightness() || 0,
                     worldview: painter.worldview
                 };
-                const featureStateChanged = withStateUpdates && bucket.stateDependentLayers.length !== 0;
-                const result = bucket.updateAppearances(this.tileID.canonical, sourceLayerStates, images, globalProperties, painter.imageManager, featureStateChanged);
+                const result = bucket.updateAppearances(this.tileID.canonical, sourceLayerStates, images, globalProperties, painter.imageManager, hasStateDependentLayers);
                 if (result && result.hasUboChanges) {
                     const context = painter.context;
                     if (bucket instanceof SymbolBucket && bucket.text && bucket.text.uboBinder) {

test/unit/source/tile.test.ts

@@ -284,6 +284,44 @@ describe('rtl text detection', () => {
     );
 });
 
+describe('Tile#updateBuckets', () => {
+    test('does not throw when feature state and a paint update land on a symbol layer with no state-dependent paint', () => {
+        const tile = new Tile(new OverscaledTileID(1, 0, 1, 1, 1), 512, 22);
+        const symbolBucket = createSymbolBucket('test', 'Test', 'test', new CollisionBoxArray());
+        // Force UBO binder creation: the crash only happens on the UBO-based update path in
+        // SymbolBucket#update, which is skipped entirely when text/icon.uboBinder is null.
+        symbolBucket.createArrays();
+
+        const layer = symbolBucket.layers[0];
+        const painter = createPainter({
+            hasLayer: () => true,
+            listImages: () => [],
+            getBrightness: () => 0,
+            getLayerSourceCache: () => undefined,
+            getLayer: () => layer,
+            getOwnLayer: () => layer
+        });
+
+        tile.loadVectorData(
+            createVectorData({rawTileData: rawTileData as ArrayBuffer, buckets: [symbolBucket]}),
+            painter
+        );
+
+        // createSymbolBucket() gives the layer only layout properties (text-font, text-field);
+        // its paint is left at defaults, so it never reads feature-state and stateDependentLayers
+        // stays empty even though the source below carries feature state.
+        expect(tile.buckets[layer.fqid].stateDependentLayers).toEqual([]);
+
+        expect(() => tile.updateBuckets(
+            painter,
+            false,                                      // isBrightnessChanged
+            {_geojsonTileLayer: {'1': {hover: true}}},   // states -> withStateUpdates = true
+            false,                                       // needsSymbolUBOUpdate
+            new Set([layer.fqid])                        // updatedPaintProps -> hasPaintUpdate = true
+        )).not.toThrow();
+    });
+});
+
 function createVectorData(options?: {buckets?: Bucket[]; rawTileData?: ArrayBuffer}): WorkerSourceVectorTileResult {
     const collisionBoxArray = new CollisionBoxArray();
     return ({collisionBoxArray: deserialize(serialize(collisionBoxArray)),