Refactor file download handling to improve error management and user notifications

main.js

@@ -225,20 +225,42 @@ electron.ipcMain.on("file_submit", async (event, args) => {
     }
 })
 
-ipcMain.handle("file_download", async () => {
+electron.ipcMain.on("file_download", async (event) => {
   try {
-    const format = globalArgs.document.outputType.replace('.', '').toLowerCase();
+    if (!globalFinalHtmlPath) {
+      throw new Error("No document generated yet");
+    }
 
-    return await mapFunctions
+    const format = String(globalArgs?.document?.outputType || "")
+      .replace('.', '')
+      .toLowerCase();
+
+    if (!format) {
+      throw new Error("No output format selected");
+    }
+
+    const outputPath = await mapFunctions
       .get("htmlDocumentConverter")
       .convert({
         inputPath: globalFinalHtmlPath,
         format,
         showDialog: true
       });
+
+    event.sender.send("download_success", {
+      path: outputPath,
+      format
+    });
+
+    new Notification({
+      title: "Erfolgreich gespeichert",
+      body: `Dokument gespeichert als .${format}`
+    }).show();
+
   } catch (err) {
-    console.error("Download failed:", err);
-    throw err;
+    console.error("file_download failed:", err);
+
+    event.sender.send("error", err.message || String(err));
   }
 });