FileExistsException example

throw new DirectoryNotReadyException("The specified file '$original_source' could not be copied because the destination directory '$dirname' is not properly configured. This may be caused by a problem with file or directory permissions.");
      }
    }

    // Determine whether we can perform this operation based on overwrite rules.     $destination = $this->getDestinationFilename($destination, $replace);
    if ($destination === FALSE) {
      $this->logger->error("File '%original_source' could not be copied because a file by that name already exists in the destination directory ('%destination').", [
        '%original_source' => $original_source,
        '%destination' => $destination,
      ]);
      throw new FileExistsException("File '$original_source' could not be copied because a file by that name already exists in the destination directory ('$destination').");
    }

    // Assert that the source and destination filenames are not the same.     $real_source = $this->realpath($source);
    $real_destination = $this->realpath($destination);
    if ($source == $destination || ($real_source !== FALSE) && ($real_source == $real_destination)) {
      $this->logger->error("File '%source' could not be copied because it would overwrite itself.", [
        '%source' => $source,
      ]);
      throw new FileException("File '$source' could not be copied because it would overwrite itself.");
    }
  }

    // Call an event to sanitize the filename and to attempt to address security     // issues caused by common server setups.     $event = new FileUploadSanitizeNameEvent($originalName, $extensions);
    $this->eventDispatcher->dispatch($event);
    $filename = $event->getFilename();

    $mimeType = $this->mimeTypeGuesser->guessMimeType($filename);
    $destinationFilename = $this->fileSystem->getDestinationFilename($destination . $filename, $replace);
    if ($destinationFilename === FALSE) {
      throw new FileExistsException(sprintf('Destination file "%s" exists', $destinationFilename));
    }

    $file = File::create([
      'uid' => $this->currentUser->id(),
      'status' => 0,
      'uri' => $uploadedFile->getRealPath(),
    ]);

    // This will be replaced later with a filename based on the destination.     $file->setFilename($filename);
    $file->setMimeType($mimeType);