color_continuous_scale causes a bug when the last item is not 1.0

import plotly.express as px
import numpy as np

df = px.data.gapminder().query("year == 2007")
fig = px.treemap(df, path=[px.Constant("world"), 'continent', 'country'], values='pop',
                  color='lifeExp', hover_data=['iso_alpha'],
                  color_continuous_scale=[(0, 'red'), (0.4, 'yellow'), (1.0, 'green')],
                  color_continuous_midpoint=np.average(df['lifeExp'], weights=df['pop']))
fig.update_layout(margin = dict(t=50, l=25, r=25, b=25))
fig.show()

This gives me the result I want.

However, something like:

                  color_continuous_scale=[(0, 'red'), (0.4, 'yellow'), (0.8, 'green')],

creates a whole separate treemap.

This fixes the issue:

                  color_continuous_scale=[(0, 'red'), (0.4, 'yellow'), (0.8, 'green')], (1.0, 'green')],

I'm not sure if there's anything to even technically "fix" here, but it was expected behaviour that I didn't get.

Start by running the provided Plotly Express treemap reproduction and inspect how color_continuous_scale is handled for treemaps. Confirm the behavior when the final scale position is below 1.0, then add a regression test showing that it does not create a separate treemap and preserves the expected coloring.