[BUG]multi_line doesn't support hover.

[ruoyu0088]

bokeh 2.2.1

test code

from bokeh.models import ColumnDataSource, HoverTool
from bokeh.plotting import figure
from bokeh.io import show

source = ColumnDataSource(data=dict(xs=[[1, 2], [3, 4]], ys=[[1, 2], [2, 1]], name=['A', 'B']))
fig = figure()
lines = fig.multi_line('xs', 'ys', source=source)
hover = HoverTool(tooltips=[('name', '@name')], renderers=[lines])
fig.add_tools(hover)
show(fig)

when hover a line, the follow exception raised in devtool console:

7VM425 bokeh-2.2.1.js:40248 Uncaught TypeError: Cannot read property '0' of undefined
    at HoverToolView._update (VM425 bokeh-2.2.1.js:40248)
    at HoverToolView.new_slot (VM425 bokeh-2.2.1.js:7546)
    at Signal.emit (VM425 bokeh-2.2.1.js:2699)
    at SelectionManager.inspect (VM425 bokeh-2.2.1.js:10912)
    at HoverToolView._inspect (VM425 bokeh-2.2.1.js:40164)
    at HoverToolView._move (VM425 bokeh-2.2.1.js:40149)
    at HoverToolView.<anonymous> (VM425 bokeh-2.2.1.js:34754)
    at HoverToolView.new_slot (VM425 bokeh-2.2.1.js:7546)
    at Signal.emit (VM425 bokeh-2.2.1.js:2699)
    at UIEvents.trigger (VM425 bokeh-2.2.1.js:34925)

Here is the code that raise the exception:

let data_x = glyph._xs[i][j];

Here is some debug information in the console.

> glyph._xs
RaggedArray {offsets: Uint32Array(2), array: Float32Array(4)}

> glyph._xs[0]
undefined

[jstmn]

What was the resolution to this? I'm running bokeh 2.2.3 and am getting this issue.

Thanks