[android] - null check source before removing

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/maps/NativeMapView.java

@@ -759,9 +759,13 @@ final class NativeMapView {
       return null;
     }
     Source source = getSource(sourceId);
-    return removeSource(source);
+    if (source != null) {
+      return removeSource(source);
+    }
+    return null;
   }
 
+  @Nullable
   public Source removeSource(@NonNull Source source) {
     if (isDestroyedOn("removeSource")) {
       return null;

platform/android/MapboxGLAndroidSDKTestApp/src/androidTest/java/com/mapbox/mapboxsdk/testapp/style/RuntimeStyleTests.java

@@ -280,6 +280,20 @@ public class RuntimeStyleTests extends BaseActivityTest {
     });
   }
 
+  @Test
+  public void testRemoveNonExistingSource() {
+    invoke(mapboxMap, (uiController, mapboxMap) -> mapboxMap.removeSource("source"));
+  }
+
+  @Test
+  public void testRemoveNonExistingLayer() {
+    invoke(mapboxMap, (uiController, mapboxMap) -> {
+      mapboxMap.removeLayer("layer");
+      mapboxMap.removeLayerAt(mapboxMap.getLayers().size() + 1);
+      mapboxMap.removeLayerAt(-1);
+    });
+  }
+
   /**
    * https://github.com/mapbox/mapbox-gl-native/issues/7973
    */