Preclude cancelation of pre-uploaded video attachments.

Addresses ##10225.

app/src/main/java/org/thoughtcrime/securesms/conversation/v2/ConversationFragment.kt

@@ -1941,6 +1941,10 @@ class ConversationFragment :
         onComplete = {
           onSendComplete()
           afterSendComplete()
+        },
+        onError = {
+          Log.w(TAG, "Error received during send!", it)
+          toast(R.string.ConversationActivity_error_sending_media)
         }
       )
   }

app/src/main/java/org/thoughtcrime/securesms/conversation/v2/ConversationRepository.kt

@@ -225,7 +225,7 @@ class ConversationRepository(
           emitter.onComplete()
         }
       } else {
-        MessageSender.sendPushWithPreUploadedMedia(
+        val sendSuccessful = MessageSender.sendPushWithPreUploadedMedia(
           AppDependencies.application,
           message,
           preUploadResults,
@@ -233,6 +233,10 @@ class ConversationRepository(
         ) {
           emitter.onComplete()
         }
+
+        if (!sendSuccessful) {
+          emitter.tryOnError(IllegalStateException("Could not send pre-uploaded attachments because they did not exist!"))
+        }
       }
     }