Catch errors when inputting an invalid file in web app #284

'utf-8', b'PK\x03\x04\x14\x00\x00\x00\x00\x00`j\x88T\t\xbe\x98\x13\x7f\x1f\x00\x00\x7f\x1f\x00\x00!\x00\x00\x00comparison_1_SctW_WT_Kinetics.pmlset_c

  File "C:\Users\jhs\Miniconda3\envs\py38_pyhdx_deploy\lib\site-packages\panel\param.py", line 449, in link_widget
    self.object.param.set_param(**{p_name: change.new})
  File "C:\Users\jhs\Miniconda3\envs\py38_pyhdx_deploy\lib\site-packages\param\parameterized.py", line 1904, in set_param
    return self_.update(kwargs)
  File "C:\Users\jhs\Miniconda3\envs\py38_pyhdx_deploy\lib\site-packages\param\parameterized.py", line 1877, in update
    self_._batch_call_watchers()
  File "C:\Users\jhs\Miniconda3\envs\py38_pyhdx_deploy\lib\site-packages\param\parameterized.py", line 2038, in _batch_call_watchers
    self_._execute_watcher(watcher, events)
  File "C:\Users\jhs\Miniconda3\envs\py38_pyhdx_deploy\lib\site-packages\param\parameterized.py", line 2000, in _execute_watcher
    watcher.fn(*args, **kwargs)
  File "C:\Users\jhs\Miniconda3\envs\py38_pyhdx_deploy\lib\site-packages\param\parameterized.py", line 649, in caller
    return function()
  File "C:\Users\jhs\Miniconda3\envs\py38_pyhdx_deploy\lib\site-packages\param\parameterized.py", line 387, in _depends
    return func(*args, **kw)
  File "C:\Users\jhs\Programming\pyhdx_deploy\pyhdx\web\controllers.py", line 395, in _read_files
    *[
  File "C:\Users\jhs\Programming\pyhdx_deploy\pyhdx\web\controllers.py", line 396, in <listcomp>
    StringIO(byte_content.decode("UTF-8"))
UnicodeDecodeError: 'utf-8' codec can't decode byte 0x88 in position 12: invalid start byte