Fix holding invalid reference to synthetic event

src/App.css

@@ -25,6 +25,7 @@
 .level-entity {
   position: absolute;
   z-index: 10;
+  image-rendering: crisp-edges;
 }
 
 .render-controls {

src/App.js

@@ -42,7 +42,10 @@ class App extends Component<{}> {
         );
     }
 
-    set = (name, value = null) => e => this.setState(s => ({ [name]: value && value.call ? value(s) : value || e.currentTarget.value }))
+    set = (name, value = null) => e => {
+        const targetValue = e.currentTarget.value
+        this.setState(s => ({ [name]: value && value.call ? value(s) : value || targetValue }))
+    }
 }
 
 export default App;