v8 audit Layer#isLoaded implementations (#8290)

Signed-off-by: Chris Gervang <chris@gervang.com>

modules/geo-layers/src/terrain-layer/terrain-layer.ts

@@ -136,7 +136,7 @@ export default class TerrainLayer<ExtraPropsT extends {} = {}> extends Composite
 
   state!: {
     isTiled?: boolean;
-    terrain: MeshAttributes;
+    terrain?: MeshAttributes;
     zRange?: ZRange | null;
   };
 
@@ -343,6 +343,10 @@ export default class TerrainLayer<ExtraPropsT extends {} = {}> extends Composite
       );
     }
 
+    if (!elevationData) {
+      return null;
+    }
+
     const SubLayerClass = this.getSubLayerClass('mesh', SimpleMeshLayer);
     return new SubLayerClass(
       this.getSubLayerProps({

modules/geo-layers/src/wms-layer/wms-layer.ts

@@ -85,7 +85,7 @@ export class WMSLayer<ExtraPropsT extends {} = {}> extends CompositeLayer<
   /** Returns true if all async resources are loaded */
   get isLoaded(): boolean {
     // Track the explicit loading done by this layer
-    return Boolean(this.state) && this.state.loadCounter === 0 && super.isLoaded;
+    return this.state?.loadCounter === 0 && super.isLoaded;
   }
 
   /** Lets deck.gl know that we want viewport change events */

modules/mesh-layers/src/scenegraph-layer/scenegraph-layer.ts

@@ -240,6 +240,10 @@ export default class ScenegraphLayer<DataT = any, ExtraPropsT extends {} = {}> e
     this._deleteScenegraph();
   }
 
+  get isLoaded(): boolean {
+    return this.state?.scenegraph && super.isLoaded;
+  }
+
   private _updateScenegraph(): void {
     const props = this.props;
     const {gl} = this.context;

modules/mesh-layers/src/simple-mesh-layer/simple-mesh-layer.ts

@@ -348,6 +348,10 @@ export default class SimpleMeshLayer<DataT = any, ExtraPropsT extends {} = {}> e
       .draw();
   }
 
+  get isLoaded(): boolean {
+    return this.state?.model && super.isLoaded;
+  }
+
   protected getModel(mesh: Mesh): Model {
     const model = new Model(this.context.gl, {
       ...this.getShaders(),