Infinite loading spinner when upgrading plotly express DH dependencies to 0.60.0

[bmingles]

Description

Upgrading Plotly express plugin dependencies to DH 0.60.0 causes the loading spinner to never go away.

Steps to reproduce

• Upgrade dh dependencies to 0.60.0 in plugins/plotly-express/src/js/package.json
• Run the plugins repo locally via npm start
• Configure proxy port VITE_JS_PLUGINS_DEV_PORT=4100 in DHC packages/code-studio/.env.development.local
• Run the following code:

from deephaven import empty_table
import deephaven.plot.express as dx

y = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K']

data = map(
    lambda x,i: f"{x}=X*EvenOdd+{i * 20}",
    y,
    range(len(y)))

t = empty_table(100).update([
    "X=ii",
    "EvenOdd = X % 2 / 4",
    ] + list(data))

p1 = dx.line(t, x="X", y=y)

Expected results

Loading spinner on chart should go away after data is loaded

Actual results

Loading spinner stays forever

Additional details and attachments

This seems to have been introduced by https://github.com/deephaven/web-client-ui/pull/1729/files , but the underlying issue seems to be we are never firing the EVENT_LOADFINISHED event from plotly express.

Versions

Web UI Version: 0.60.0