small batches with no results make parquets not loadable via glob

[banteg]

how to replicate

pdp collect ethereum_contracts -b 16800000:16800100:10 -s -f parquet

import polars as pl
df = pl.scan_parquet('*.parquet')
# ComputeError: error while reading ethereum_contracts__v1_1_0__16800030_to_16800039.parquet: External format error: File out of specification: Repetition level must be defined for a primitive type

df = pl.scan_parquet('ethereum_contracts__v1_1_0__16800030_to_16800039.parquet')
# ArrowErrorException: ExternalFormat("File out of specification: Repetition level must be defined for a primitive type")

it appears that when a batch doesn't produce results, no schema is written to a parquet file, which makes it impossible to load it via glob.