New streaming quietly ignores failing source when sinking

[coastalwhite]

Checks

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of Polars.

Reproducible example

import polars as pl
import os

os.environ['POLARS_FORCE_NEW_STREAMING'] = '1'
# Scanning an non-existent file
pl.scan_parquet('sadlfjalsfj').sink_ipc('x.ipc')

Log output

Issue description

No error is thrown.

Expected behavior

An error is thrown.

Installed versions

Replace this line with the output of pl.show_versions(). Leave the backticks in place.