demo(12-missing-null-guard): 12 — New public method takes a nullable string with no guard

[EricCogen]

12 — New public method takes a nullable string with no guard

Expected verdict: ❌ Fails — GauntletCI should fire GCI0006 (edge case handling).

What changed

A new CustomerNoteFormatter exposes a public method that accepts a
nullable string? and immediately dereferences it without any
runtime check:

public sealed class CustomerNoteFormatter
{
    public string Format(string? note)
    {
        return note!.Trim().ToUpperInvariant();
    }
}

The compiler is silenced with ! (so the build still succeeds), but
the runtime behaviour is unchanged — calling Format(null) throws
NullReferenceException deep inside Trim.

Why this is risky

• The signature openly accepts null (string?), so callers are
  entitled to pass it. Nothing in the body translates that into a
  documented ArgumentNullException or a sensible default.
• NullReferenceException thrown from a transitive callee is one of
  the worst error shapes to debug: the stack trace points at Trim,
  not at the caller that handed in null.
• A single ArgumentNullException.ThrowIfNull(note) (or a ??
  fallback) makes the contract explicit.

What GauntletCI catches

GCI0006 Edge Case Handling — a public method whose signature
declares a nullable reference parameter (string? / object?) and
whose first few lines contain no null check, throw, or
ArgumentNullException guard.

[github-actions]

GauntletCI found issues in this PR. See inline comments for details.

[github-actions]

GCI0006 — Edge Case Handling

New method parameter(s) added without apparent null/range validation in src/OrderService/Pricing/CustomerNoteFormatter.cs

Evidence:

Line 5: public string Format(string? note)

⚠️ Why it matters: Unvalidated parameters can lead to NullReferenceException or incorrect behaviour deeper in the call stack.

💡 Suggested action: Add ArgumentNullException.ThrowIfNull() or similar guard at the top of the method.

_{Confidence: Medium | Severity: Warn}

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Guard nullable note before calling Trim

Format declares note as nullable (string?) but immediately dereferences it via note! and calls Trim, so Format(null) will throw a NullReferenceException from inside Trim instead of failing fast with a clear argument validation error. Since this is a public method, callers are allowed by the signature to pass null; add an explicit null guard (or fallback behavior) at the method boundary.

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