Warning Types

Errors

Catch-All Blocking

Message: "Row X is a catch-all. Rows Y, Z will never be reached."

A row with "any" for all conditions matches everything, blocking all rows below it.

Row 1: If tier = "gold" → Discount 20%
Row 2: If any → Discount 0%  ← Catch-all
Row 3: If tier = "platinum" → Discount 30%  ← Never reached!

Fix: Move the catch-all to the bottom.

Row 1: If tier = "gold" → Discount 20%
Row 2: If tier = "platinum" → Discount 30%
Row 3: If any → Discount 0%  ← Now at the bottom

Unreachable Row

Message: "Row X is unreachable because it is fully covered by Row Y."

Every input that would match Row X is already caught by an earlier row.

Row 1: If score >= 700 → Approved
Row 2: If score >= 750 → Premium  ← Unreachable!

Any score >= 750 also satisfies >= 700, so Row 1 catches it first.

Fix: Reorder so the more specific condition comes first:

Row 1: If score >= 750 → Premium
Row 2: If score >= 700 → Approved

Warnings

Partial Overlap

Message: "Row X partially overlaps with Row Y."

Some inputs match both rows, but not all. The earlier row wins for the overlap.

Row 1: If tier = "gold" AND score > 600 → Plan A
Row 2: If score > 700 → Plan B

A gold-tier customer with score 750 matches both, but gets Plan A.

Fix: If unintentional, make conditions mutually exclusive. If intentional, document why and ignore the warning.

💡

Partial overlaps aren't always bugs—sometimes you want earlier rows to take precedence.

Coverage Gap

Message: "Column 'X' has a coverage gap: values in [a, b] have no explicit handling."

There's a range of values that won't match any row.

Row 1: If age < 18 → Minor rate
Row 2: If age > 65 → Senior rate
← Gap: Ages 18-65 have no explicit handling

Fix: Add a row for the missing range, or verify your catch-all handles it correctly.

Boundary Gap

Message: "Exact value X = 100 has no explicit handling."

Adjacent conditions leave a specific value unhandled.

Row 1: If score < 100 → Fail
Row 2: If score > 100 → Pass
← Gap: Exactly 100 falls through!

Fix: Use inclusive operators:

Row 1: If score < 100 → Fail
Row 2: If score >= 100 → Pass

Info

Incomplete Coverage

Message: "No catch-all row exists. Some inputs may not match any row."

Without a catch-all, unmatched inputs return an error.

Fix: Add a final row with "any" for all conditions if you want a default result. Leave it out if you want unhandled cases to error.

💡

This is informational—intentionally omitting a catch-all is valid when you want unhandled cases flagged as errors.

🚫

It is important to note that warnings aren't always available. Warnings don't appear when your rule uses row groups with priorities, individual row priorities, or OR rows. These features change evaluation semantics in ways static analysis can't predict—use Reachability Analysis for runtime validation instead.

Overview Creating a Form