dashboard: properly remove charts on widget close action

src/opnsense/www/js/widgets/Disk.js

@@ -248,4 +248,14 @@ export default class Disk extends BaseWidget {
         }
     }
 
+    onWidgetClose() {
+        if (this.simple_chart !== null) {
+            this.simple_chart.destroy();
+        }
+
+        if (this.detailed_chart !== null) {
+            this.detailed_chart.destroy();
+        }
+    }
+
 }

src/opnsense/www/js/widgets/Firewall.js

@@ -288,6 +288,10 @@ export default class Firewall extends BaseTableWidget {
         if (this.eventSource !== null) {
             this.eventSource.close();
         }
+
+        if (this.chart !== null) {
+            this.chart.destroy();
+        }
     }
 
     onWidgetResize(elem, width, height) {

src/opnsense/www/js/widgets/InterfaceStatistics.js

@@ -185,4 +185,10 @@ export default class InterfaceStatistics extends BaseWidget {
         return true;
     }
 
+    onWidgetClose() {
+        if (this.chart !== null) {
+            this.chart.destroy();
+        }
+    }
+
 }

src/opnsense/www/js/widgets/Memory.js

@@ -129,4 +129,10 @@ export default class Memory extends BaseWidget {
             }
         });
     }
+
+    onWidgetClose() {
+        if (this.chart !== null) {
+            this.chart.destroy();
+        }
+    }
 }