Example stacked bar chart doesn't work with Polars in v5 rc

[braaannigan]

If we try the example stacked bar chart but convert to Polars it doesn't work (I found this with a similar error on my own data):

import altair as alt
from vega_datasets import data
import polars as pl

source = pl.from_pandas(data.seattle_weather())

alt.Chart(source).mark_bar(
    cornerRadiusTopLeft=3,
    cornerRadiusTopRight=3
).encode(
    x='month(date):O',
    y='count():Q',
    color='weather:N'
)

with error message:

thread 'tokio-runtime-worker' panicked at 'assertion failed: `(left == right)`
  left: `LargeUtf8`,
 right: `Utf8`: StringArray expects DataType::Utf8', /root/.cargo/registry/src/github.jparrowsec.cn-1ecc6299db9ec823/arrow-array-32.0.0/src/array/byte_array.rs:268:9
thread 'tokio-runtime-worker' panicked at 'assertion failed: `(left == right)`
  left: `LargeUtf8`,
 right: `Utf8`: StringArray expects DataType::Utf8', /root/.cargo/registry/src/github.jparrowsec.cn-1ecc6299db9ec823/arrow-array-32.0.0/src/array/byte_array.rs:268:9
thread 'tokio-runtime-worker' panicked at 'assertion failed: `(left == right)`
  left: `LargeUtf8`,
 right: `Utf8`: StringArray expects DataType::Utf8thread '', tokio-runtime-worker/root/.cargo/registry/src/github.jparrowsec.cn-1ecc6299db9ec823/arrow-array-32.0.0/src/array/byte_array.rs' panicked at ':assertion failed: `(left == right)`
  left: `LargeUtf8`,
 right: `Utf8`: StringArray expects DataType::Utf8268', :/root/.cargo/registry/src/github.jparrowsec.cn-1ecc6299db9ec823/arrow-array-32.0.0/src/array/byte_array.rs9:
268:9
thread 'tokio-runtime-worker' panicked at 'assertion failed: `(left == right)`
  left: `LargeUtf8`,
 right: `Utf8`: StringArray expects DataType::Utf8', /root/.cargo/registry/src/github.jparrowsec.cn-1ecc6299db9ec823/arrow-array-32.0.0/src/array/byte_array.rs:268:9
thread 'tokio-runtime-worker' panicked at 'assertion failed: `(left == right)`
  left: `LargeUtf8`,
 right: `Utf8`: StringArray expects DataType::Utf8', /root/.cargo/registry/src/github.jparrowsec.cn-1ecc6299db9ec823/arrow-array-32.0.0/src/array/byte_array.rs:268:9

[jonmmease]

Hi @braaannigan, are you running this example with VegaFusion? It's not in your example. but the stack trace looks like it might be related to VegaFusion.

[braaannigan]

Hi @jonmmease, yes, sorry that import was elsewhere in the notebook

[jonmmease]

No worries, thanks for taking the time to report it!
Lets move discussion over to vega/vegafusion#286 and close the issue here.

[joelostblom]

Closing in favor of the vegafusion issue