fix(canvas): error when trying to save due to uninitialized API

apps/client/src/widgets/type_widgets/canvas.ts

@@ -357,6 +357,9 @@ export default class ExcalidrawTypeWidget extends TypeWidget {
         if (options.is("databaseReadonly")) {
             return;
         }
+
+        if (!this.canvasInstance.isInitialized()) return;
+
         // changeHandler is called upon any tiny change in excalidraw. button clicked, hover, etc.
         // make sure only when a new element is added, we actually save something.
         const isNewSceneVersion = this.canvasInstance.isNewSceneVersion();

apps/client/src/widgets/type_widgets/canvas_el.tsx

@@ -76,6 +76,10 @@ export default class Canvas {
         return this.currentSceneVersion === SCENE_VERSION_INITIAL;
     }
 
+    isInitialized() {
+        return !!this.excalidrawApi;
+    }
+
     resetScene(theme: Theme) {
         this.excalidrawApi.updateScene({
             elements: [],
@@ -194,4 +198,4 @@ function CanvasElement(opts: ExcalidrawProps) {
             />
         </div>
     );
-}
+}