fix: clean up FFmpeg log listener correctly

Author: riya-chauhan12

src/lib/ffmpeg.worker.ts

@@ -486,7 +486,7 @@ async function runExport(request: ExportRequest): Promise<ResultPayload> {
     }
 
     let missingAudioDetected = false;
-    const logListener = ({ message }: { message: string }) => {
+    logListener = ({ message }: { message: string }) => {
       const msg = message.toLowerCase();
       if (
         msg.includes("matches no streams") ||
@@ -691,4 +691,4 @@ self.addEventListener("message", (event) => {
   handleCommand(event.data as WorkerCommand).catch((error) => {
     postMessage({ type: "error", message: (error as Error).message });
   });
-});
+});