refactor: improve file handling in VideoMediaController to support multipart uploads and enhance error handling

apps/box-mgnt-api/src/mgnt-backend/feature/video-media/video-media.controller.ts

@@ -316,17 +316,22 @@ export class VideoMediaController {
 
     // fastify multipart
     const reqAny = req as any;
-    const bodyFile = reqAny.body?.file;
-    let mpFile = Array.isArray(bodyFile) ? bodyFile[0] : bodyFile;
-    if (!mpFile && reqAny.isMultipart?.()) {
-      mpFile = await reqAny.file();
+    let buf: Buffer | undefined;
+
+    if (reqAny.isMultipart?.() && typeof reqAny.file === 'function') {
+      const part = await reqAny.file();
+      buf = await getBuffer(part);
     }
 
-    if (!mpFile) {
-      throw new BadRequestException('No file uploaded');
+    if (!buf) {
+      const bodyFile = reqAny.body?.file;
+      const mpFile = Array.isArray(bodyFile) ? bodyFile[0] : bodyFile;
+      buf = await getBuffer(mpFile);
     }
 
-    const buf = await getBuffer(mpFile);
+    if (!buf) {
+      throw new BadRequestException('No file uploaded');
+    }
 
     if (!buf?.length) {
       throw new BadRequestException('Empty file');