Don't treat failure to send as an error

If the file reader task fails to send a chunk to an upload task, we know
this is because that task has either returned due to an error or
panicked. In either case this isn't an error for the reader, which
should return early as the overall request will fail.

sdk/src/extras/disk.rs

@@ -392,13 +392,14 @@ pub mod types {
                 if !chunk.iter().all(|x| *x == 0) {
                     let encoded = base64::engine::general_purpose::STANDARD.encode(&chunk[0..n]);
 
-                    if let Err(e) = senders[i % self.upload_thread_ct]
+                    if senders[i % self.upload_thread_ct]
                         .send((offset, encoded, n as u64))
                         .await
+                        .is_err()
                     {
-                        break Err(DiskImportError::other(format!(
-                            "sending chunk to thread failed: {e}"
-                        )));
+                        // Failure to send indicates that the upload task exited early
+                        // due to an error on its end. We will return that error below.
+                        break Ok(());
                     }
                 } else {
                     // Bump the progress bar here to make it consistent