code: @Nonnull
    public static FileIOError deleteFileIfExisting (@Nonnull final File aFile)
    {
      final FileIOError aError = deleteFile (aFile);
      if (aError.getErrorCode ().equals (EFileIOErrorCode.SOURCE_DOES_NOT_EXIST))
        return EFileIOErrorCode.NO_ERROR.getAsIOError (EFileIOOperation.DELETE_FILE, aFile);
      return aError;
    }
docs: Delete a file if it is existing.
  
  @param aFile
  The file to be deleted. May not be <code>null</code>.
  @return A non-<code>null</code> error code.