foreign_key_violation doesn't catch a missing trip_id

[tzujenchanmbd]

Describe the bug

When testing a feed with GTFS-flex data where there is a missing trip_id in trip.txt(parent file) but being referenced in stop_times.txt, validator doesn't show a foreign_key_violation error.

Here is the report link:
https://gtfs-validator-results.mobilitydata.org/83a0d446-3a65-4258-92c1-22b61c5dd6fe/report.html

Steps/Code to Reproduce

1. Download the test feed provided below
2. Upload the feed to Canonical GTFS Schedule Validator

Expected Results

Validator shows a foreign_key_violation error that indicates trip_id=t_5298041_b_77503_tn_0 in stop_times.txt cannot be found in trips.txt.

Actual Results

Validator doesn't show the error

Screenshots

No response

Files used

on-demand_services_between_multiple_zones.zip

Validator version

5.0.1

Operating system

MacOS

Java version

No response

Additional notes

No response

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[qcdyx]

I got too deep into analyzing the issue—it actually stems from a parsing error in the stop_times.txt file. Let's delve into how we can improve the presentation of this error for our end users.

[qcdyx]

3 of the Flex gtfs data sets got parsing issues listed here https://docs.google.com/document/d/1QABoIeOdR6lAB7A6_X6WIbZwC7EnAIZvm_hRNwNQeoI/edit#heading=h.xt9phhoxqouq
New issue created #1767