Improved scatter closing. Added module to eslint.

.eslintrc

@@ -3,7 +3,8 @@
         "ecmaVersion": 10,
         "sourceType": "module",
         "ecmaFeatures": {
-            "impliedStrict": true
+            "impliedStrict": true,
+            "modules": true
         }
     },
     "env": {

lib/scatter.js

@@ -370,9 +370,17 @@ export class AbstractScatter extends Throwable {
     }
 
     close() {
+        this._callCloseCallbacks()
+        this._removeSelfFromScatterContainer()
+    }
+
+    _callCloseCallbacks() {
         if (this.onClose) {
             this.onClose.forEach(callback => callback(this))
+        }
+    }
 
+    _removeSelfFromScatterContainer() {
         /**
             Removes self from container when it's closed.
             */
@@ -380,7 +388,6 @@ export class AbstractScatter extends Throwable {
             this.container.remove(this)
         }
     }
-    }
 
     gesture(interaction) {
         let delta = interaction.delta()
@@ -1007,7 +1014,6 @@ export class DOMScatterContainer {
         }
     }
 
-
     /**
      * Removes an element from the scatter.
      *
@@ -1015,9 +1021,15 @@ export class DOMScatterContainer {
      * @memberof DOMScatterContainer
      */
     remove(scatter) {
-        this.scatter.delete(scatter.element)
-    }
+        const element = scatter.element
+        if (!this.scatter.has(element))
+            console.warn(
+                `Try removing element that is not in the scatter.`,
+                element
+            )
 
+        this.scatter.delete(element)
+    }
 
     /**
      * Adds an element to the ScatterContainer.