BeakerX not displaying pandas tables when timestamps are columns

I have a pandas dataframe setup as the following:

```

RangeIndex: 28 entries, 0 to 27
Data columns (total 9 columns):
instance_name 28 non-null object
node_name 28 non-null object
counter_name 28 non-null object
x_label 28 non-null object
2019-05-06 06:38:00 28 non-null float64
2019-05-06 06:43:00 28 non-null float64
2019-05-06 06:48:00 28 non-null float64
2019-05-06 06:53:00 28 non-null float64
2019-05-06 06:58:00 28 non-null float64
```

When I try to display the dataframe, nothing displays. I see the following error in JavaScript console:

```
Uncaught (in promise) TypeError: Cannot read property 'index' of undefined
at selectors.ts:123
at index.js:76
at index.js:36
at index.js:90
at index.js:36
at ColumnPosition.getColumnByPosition (ColumnPosition.ts:108)
at DataGridResize.setInitialSectionWidth (DataGridResize.ts:113)
at DataGridResize.setInitialSectionWidths (DataGridResize.ts:104)
at DataGridResize.setInitialSize (DataGridResize.ts:66)
at BeakerXDataGrid.init (BeakerXDataGrid.ts:113)
at new BeakerXDataGrid (BeakerXDataGrid.ts:91)
at new DataGridScope (DataGridScope.ts:42)
at TableDisplayView.initDataGridTable (TableDisplay.ts:84)
at TableDisplay.ts:49
  | (anonymous) | @ | selectors.ts:123
-- | -- | -- | --
  | (anonymous) | @ | index.js:76
  | (anonymous) | @ | index.js:36
  | (anonymous) | @ | index.js:90
  | (anonymous) | @ | index.js:36
  | getColumnByPosition | @ | ColumnPosition.ts:108
  | setInitialSectionWidth | @ | DataGridResize.ts:113
  | setInitialSectionWidths | @ | DataGridResize.ts:104
  | setInitialSize | @ | DataGridResize.ts:66
  | init | @ | BeakerXDataGrid.ts:113
  | BeakerXDataGrid | @ | BeakerXDataGrid.ts:91
  | DataGridScope | @ | DataGridScope.ts:42
  | initDataGridTable | @ | TableDisplay.ts:84
  | (anonymous) | @ | TableDisplay.ts:49
  | Promise.then (async) |   |  
  | render | @ | TableDisplay.ts:42
  | (anonymous) | @ | manager-base.js:97
  | Promise.then (async) |   |  
  | (anonymous) | @ | manager-base.js:91
  | Promise.then (async) |   |  
  | ManagerBase.create_view | @ | manager-base.js:90
  | ManagerBase.display_model | @ | manager-base.js:71
  | (anonymous) | @ | extension.js:120
  | Promise.then (async) |   |  
  | render | @ | extension.js:119
  | append_mime | @ | extension.js:145
  | OutputArea.append_mime_type | @ | outputarea.js:696
  | OutputArea.append_display_data | @ | outputarea.js:659
  | OutputArea.append_output | @ | outputarea.js:346
  | OutputArea.handle_output | @ | outputarea.js:257
  | output | @ | codecell.js:395
  | Kernel._handle_output_message | @ | kernel.js:1196
  | i | @ | jquery.min.js:2
  | Kernel._handle_iopub_message | @ | kernel.js:1223
  | Kernel._finish_ws_message | @ | kernel.js:1015
  | (anonymous) | @ | kernel.js:1006
  | Promise.then (async) |   |  
  | Kernel._handle_ws_message | @ | kernel.js:1006
  | i | @ | jquery.min.js:2

```

Other dataframes in the same ipynb work just fine...it's just ones with timestamps as column headers. Using BeakerX 1.4.1.