fix: silence abort warning on cancel

src/server/request-handler.ts

@@ -857,7 +857,7 @@ function htmlPage(): string {
 
           for (const entry of listing) {
             if (controller.signal.aborted) {
-              throw new DOMException("Import abgebrochen", "AbortError");
+              throw controller.signal.reason ?? new Error("Import abgebrochen");
             }
 
             try {
@@ -901,7 +901,7 @@ function htmlPage(): string {
           );
           setProgress(listing.length, listing.length, "fertig");
         } catch (error) {
-          if (error instanceof DOMException && error.name === "AbortError") {
+          if (controller.signal.aborted) {
             updateStatus("Import abgebrochen.");
             setProgress(state.processed, state.total, "abgebrochen");
             return;
@@ -940,7 +940,7 @@ function htmlPage(): string {
 
       cancelShare.addEventListener("click", () => {
         if (activeImportController) {
-          activeImportController.abort();
+          activeImportController.abort("Import durch Benutzer abgebrochen");
         }
       });