fix: ignore and/or filters whose entries are all empty

[breken-ai]

What kind of change does this PR introduce?

Bug fix.

What is the current behavior?

An and/or filter whose entries are all empty fails with a raw SQL error, where it should be ignored:

{ accountCollection(filter: {or: [{}]}) { edges { node { id } } } }
# {"errors": [{"message": "syntax error at or near \")\""}]}

The same happens with and: [{}], with not: {or: [{}]}, on update/delete mutation filters, and, most commonly in practice, when an entry's only operator comes from an omitted variable:

query ($email: String) { accountCollection(filter: {or: [{email: {eq: $email}}]}) { ... } }
# variables: {}  ->  syntax error at or near ")"

create_filters drops each empty entry (the "Avoid argumentless and" branch). If nothing is left, it still pushes CompoundFilterBuilder::Or(vec![]), which transpiles to ().

What is the new behavior?

When no entries remain, the compound filter is skipped, just as or: [] / and: [] already are. The docs say "Empty filters are ignored, i.e. they behave as if the operator was not specified at all". Mixed lists are unchanged: or: [{}, {id: {eq: 2}}] still returns id 2 only.

Additional context

• New regression test test/sql/compound_filters_empty_entries.sql covers or: [{}], and: [{}], the omitted-variable case, a mixed list, not around an empty or, and an update mutation.
• Proof, run with the repo's dockerfiles/db/Dockerfile toolchain (PG 17, pgrx 0.19.2):
  • On master, every empty-entry case in the new test returns syntax error at or near ")".
  • With the fix, ./bin/installcheck passes all 123 tests.
  • cargo fmt --check and cargo clippy --features pg17 -- -D warnings are clean.

This PR was prepared with AI assistance (Claude). I reviewed and tested the change as described above.

🤖 Generated with Claude Code

[imor]

Closing as this is 100% AI generated.