Allow to start from scratch with a default config

src/App.tsx

@@ -100,8 +100,39 @@ export class App extends React.Component<IAppProps> {
           historyCurrentStep: 0,
           isLoaded: true
         });
-      }, (error) => { throw new Error(error); }
-      );
+      }, (error) => {
+        // TODO: Implement an alert component
+        console.warn('[NewEditor] Could not fetch resource from API. Returning default.', error);
+        const MainContainer = new ContainerModel(
+          null,
+          {
+            id: 'main',
+            parentId: 'null',
+            x: 0,
+            y: 0,
+            width: DEFAULT_CONFIG.MainContainer.Width,
+            height: DEFAULT_CONFIG.MainContainer.Height,
+            fillOpacity: DEFAULT_CONFIG.MainContainer.Style.fillOpacity,
+            stroke: DEFAULT_CONFIG.MainContainer.Style.stroke,
+          }
+        );
+
+        // Save the configuration and the new MainContainer
+        // and default the selected container to it
+        this.setState({
+          configuration: DEFAULT_CONFIG,
+          history:
+          [
+            {
+              MainContainer,
+              SelectedContainer: MainContainer,
+              TypeCounters: {}
+            }
+          ],
+          historyCurrentStep: 0,
+          isLoaded: true
+        });
+      });
   }
 
   public LoadEditor(files: FileList | null): void {
@@ -182,3 +213,28 @@ export async function fetchConfiguration(): Promise<Configuration> {
     xhr.send();
   });
 }
+
+
+const DEFAULT_CONFIG: Configuration = {
+  AvailableContainers: [
+    {
+      Type: 'Container',
+      Width: 75,
+      Height: 100,
+      Style: {
+        fillOpacity: 0,
+        stroke: 'green'
+      }
+    }
+  ],
+  AvailableSymbols: [],
+  MainContainer: {
+    Type: 'Container',
+    Width: 2000,
+    Height: 100,
+    Style: {
+      fillOpacity: 0,
+      stroke: 'black'
+    }
+  }
+}