fix removal of heatmap layer

before, whenever a react-leaflet map was unmounted, the heatmap Layer’s
onRemove function and the component’s componentWillUnmount would get
called.  This caused an error since the node had already been removed
from the DOM.

Author: evansiroky

lib/HeatmapLayer.js

@@ -76,6 +76,15 @@ function isValid(num) {
   return !isInvalid(num);
 }
 
+function safeRemoveLayer(map, el) {
+  var _map$getPanes = map.getPanes(),
+      overlayPane = _map$getPanes.overlayPane;
+
+  if (overlayPane.contains(el)) {
+    overlayPane.removeChild(el);
+  }
+}
+
 function shouldIgnoreLocation(loc) {
   return isInvalid(loc.lng) || isInvalid(loc.lat);
 }
@@ -124,7 +133,7 @@ var HeatmapLayer = function (_MapLayer) {
         return this;
       },
       onRemove: function onRemove(map) {
-        map.getPanes().overlayPane.removeChild(el);
+        safeRemoveLayer(map, el);
       }
     });
 
@@ -191,7 +200,7 @@ var HeatmapLayer = function (_MapLayer) {
   };
 
   HeatmapLayer.prototype.componentWillUnmount = function componentWillUnmount() {
-    this.context.map.getPanes().overlayPane.removeChild(this._el);
+    safeRemoveLayer(this.context.map, this._el);
   };
 
   HeatmapLayer.prototype.fitBounds = function fitBounds() {

package.json

@@ -28,10 +28,10 @@
   "author": "Jeremiah Hall <npm@jeremiahrhall.com>",
   "license": "MIT",
   "peerDependencies": {
-    "leaflet": "^1.0.2",
-    "react-leaflet": "^1.0.0",
-    "react": "^15.4.1",
-    "react-dom": "^15.4.1"
+    "leaflet": ">=1.0.0",
+    "react-leaflet": ">=1.0.0",
+    "react": ">=15.4.1",
+    "react-dom": ">=15.4.1"
   },
   "devDependencies": {
     "babel-cli": "^6.6.5",

src/HeatmapLayer.js

@@ -65,6 +65,13 @@ function isValid(num: number): boolean {
   return !isInvalid(num);
 }
 
+function safeRemoveLayer (map, el) {
+  const {overlayPane} = map.getPanes()
+  if (overlayPane.contains(el)) {
+    overlayPane.removeChild(el);
+  }
+}
+
 function shouldIgnoreLocation(loc: LngLat): boolean {
   return isInvalid(loc.lng) || isInvalid(loc.lat);
 }
@@ -125,7 +132,7 @@ export default class HeatmapLayer extends MapLayer {
         return this;
       },
       onRemove: function(map) {
-        map.getPanes().overlayPane.removeChild(el);
+        safeRemoveLayer(map, el)
       }
     });
 
@@ -194,7 +201,7 @@ export default class HeatmapLayer extends MapLayer {
   }
 
   componentWillUnmount(): void {
-    this.context.map.getPanes().overlayPane.removeChild(this._el);
+    safeRemoveLayer(this.context.map, this._el);
   }
 
   fitBounds(): void {