Review nits: set an interim paint in style_layer (#9688)

* set an interim paint in style_layer

* add a simple test for undefined paint

* Address review nits

* Silence inconsistent flow error

Co-authored-by: Nick Mann <nick_j_mann@uk.ibm.com>

src/source/tile.js

@@ -405,7 +405,7 @@ class Tile {
 
             bucket.update(sourceLayerStates, sourceLayer, this.imageAtlas && this.imageAtlas.patternPositions || {});
             const layer = painter && painter.style && painter.style.getLayer(id);
-            if (layer && layer.paint) {
+            if (layer) {
                 this.queryPadding = Math.max(this.queryPadding, layer.queryRadius(bucket));
             }
         }

src/style/style_layer.js

@@ -10,7 +10,7 @@ import {
     emitValidationErrors
 } from './validate_style';
 import {Evented} from '../util/evented';
-import {Layout, Transitionable, Transitioning, Properties, PossiblyEvaluatedPropertyValue} from './properties';
+import {Layout, Transitionable, Transitioning, Properties, PossiblyEvaluated, PossiblyEvaluatedPropertyValue} from './properties';
 import {supportsPropertyExpression} from '../style-spec/util/properties';
 
 import type {FeatureState} from '../style-spec/expression';
@@ -100,6 +100,8 @@ class StyleLayer extends Evented {
             }
 
             this._transitioningPaint = this._transitionablePaint.untransitioned();
+            //$FlowFixMe
+            this.paint = new PossiblyEvaluated(properties.paint);
         }
     }
 

test/unit/style/style_layer.test.js

@@ -403,5 +403,12 @@ test('StyleLayer#serialize', (t) => {
         t.end();
     });
 
+    t.test('layer.paint is never undefined', (t) => {
+        const layer = createStyleLayer({type: 'fill'});
+        // paint is never undefined
+        t.ok(layer.paint);
+        t.end();
+    });
+
     t.end();
 });