DataTable selectable='checkbox' gives JavaScript error

[markusdr]

ALL software version info (bokeh, python, notebook, OS, browser, any other relevant packages)

bokeh 0.13.0
python 3.6.5
Mac OS Sierra 10.12.6
Got same JavaScript error in:
Chrome Version 67.0.3396.87 (Official Build) (64-bit) and
Safari Version 11.1.1 (12605.2.8)

Description of expected behavior and the observed behavior

It should show a DataTable with checkboxes for row selection, as described in the DataTable help:

selectable = Either(Bool(True), Enum("checkbox"), help="""
    Whether a table's rows can be selected or not. Using ``checkbox`` is
    equivalent  to ``True``, but makes selection visible through a checkbox
    for each row,  instead of highlighting rows. Multiple selection is
    allowed and can be achieved by either clicking multiple checkboxes (if
    enabled) or using Shift + click on rows.

But nothing is shown, and a JavaScript error occurs, see below.

Complete, minimal, self-contained example code that reproduces the issue

from datetime import date
from random import randint

from bokeh.io import output_file, show
from bokeh.layouts import widgetbox
from bokeh.models import ColumnDataSource
from bokeh.models.widgets import DataTable, DateFormatter, TableColumn

output_file("data_table.html")

data = dict(
            dates=[date(2014, 3, i+1) for i in range(10)],
            downloads=[randint(0, 100) for i in range(10)],
        )
source = ColumnDataSource(data)

columns = [
            TableColumn(field="dates", title="Date", formatter=DateFormatter()),
            TableColumn(field="downloads", title="Downloads"),
        ]
data_table = DataTable(source=source, columns=columns, width=400, height=280, selectable='checkbox')

show(widgetbox(data_table))

Stack traceback and/or browser JavaScript console output

Uncaught Error: Bool property 'selectable' given invalid value: "checkbox"
    at e.validate (bokeh-0.13.0.min.js:31)
    at e.t._init (bokeh-0.13.0.min.js:31)
    at e.t.update (bokeh-0.13.0.min.js:31)
    at e.u.finalize (bokeh-0.13.0.min.js:31)
    at bokeh-0.13.0.min.js:31
    at _ (bokeh-0.13.0.min.js:31)
    at _ (bokeh-0.13.0.min.js:31)
    at Function.P._initialize_references_json (bokeh-0.13.0.min.js:31)
    at Function.P.from_json (bokeh-0.13.0.min.js:31)
    at bokeh-0.13.0.min.js:31

Screenshots or screencasts of the bug in action

[2torus]

@bryevdv I think the issue is the difference between data_table.ts line 277
and data_table.ts line 307
I think 307 should be selectable: [ p.Any, true]. Changing this worked for me.