Fix coalesce error in ofec_filings_all_mv

[hcaofec]

Summary (required)

• Resolves Fix null committee_name in ts_vector column used by q_filer  #5416

Fix the coalesce error.

Required reviewers

1 developer

How to test

1. Download feature branch
2. Run pytest
3. Run Flyway migrate
4. Test filings endpoint on local by switching model to tmp mv

In common/models/filings.py, set

class Filings(FecFileNumberMixin, CsvMixin, db.Model):
tablename = 'ofec_filings_all_mv_tmp_hc'

Before change, no rows returned
https://api.open.fec.gov/v1/filings/?sort=-receipt_date&sort_hide_null=false&sort_nulls_last=false&per_page=20&page=1&sort_null_only=false&q_filer=C00780197&api_key=DEMO_KEY
After change, 9 rows returned
http://127.0.0.1:5000/v1/filings/?page=1&sort_nulls_last=false&q_filer=C00780197&sort=-receipt_date&sort_hide_null=false&per_page=20&sort_null_only=false

[fec-jli]

Looks good.