Fix: handlers not retained unless callers retain the MuxUpload (#25)

* fix: Retain MuxUploader & Handlers via the UploadManager

* Also clear the delegate

Author: daytime-em

Sources/MuxUploadSDK/PublicAPI/MuxUpload.swift

@@ -187,7 +187,7 @@ public final class MuxUpload : Hashable, Equatable {
         let fileWorker = ChunkedFileUploader(uploadInfo: uploadInfo, startingAtByte: completedUnitCount)
         fileWorker.addDelegate(
             withToken: id,
-            InternalUploaderDelegate { [weak self] state in self?.handleStateUpdate(state) }
+            InternalUploaderDelegate { [self] state in handleStateUpdate(state) }
         )
         fileWorker.start()
         uploadManager.registerUploader(fileWorker, withId: id)
@@ -223,6 +223,7 @@ public final class MuxUpload : Hashable, Equatable {
                 let finalStatus = Status(progress: result.finalProgress, updatedTime: result.finishTime, startTime: result.startTime, isPaused: false)
                 notifySuccess(Result<Success, UploadError>.success(Success(finalState: finalStatus)))
             }
+            fileWorker?.removeDelegate(withToken: id)
             fileWorker = nil
         }
         case .failure(let error): do {
@@ -241,6 +242,7 @@ public final class MuxUpload : Hashable, Equatable {
                     notifyFailure(Result.failure(parsedError))
                 }
             }
+            fileWorker?.removeDelegate(withToken: id)
             fileWorker = nil
         }
         case .uploading(let update): do {