Add note about custom errors

desktop/src/preload.ts

@@ -271,6 +271,20 @@ export async function computeTextEmbedding(
 
 // -
 
+/**
+ * [Note: Custom errors across Electron/Renderer boundary]
+ *
+ * We need to use the `message` field to disambiguate between errors thrown by
+ * the main process when invoked from the renderer process. This is because:
+ *
+ * > Errors thrown throw `handle` in the main process are not transparent as
+ * > they are serialized and only the `message` property from the original error
+ * > is provided to the renderer process.
+ * >
+ * > - https://www.electronjs.org/docs/latest/tutorial/ipc
+ * >
+ * > Ref: https://github.com/electron/electron/issues/24427
+ */
 /* preload: duplicated CustomErrors */
 const CustomErrorsP = {
     WINDOWS_NATIVE_IMAGE_PROCESSING_NOT_SUPPORTED: