Address additional Copilot AI feedback

1. Fix potential NullReferenceException in GetHashCode()
   - Changed from CSharpType.GetHashCode() to HashCode.Combine(CSharpType)
   - HashCode.Combine handles null values properly

2. Update CHANGELOG for accuracy
   - Clarify that string/byte[] compare _maxWidthForStrings (backing field)
   - Not the Width property which includes Size.ToStringLength()
   - Add note about avoiding Size interference
   - Mention null-safety improvement in GetHashCode()
   - Update test count to 19 (added 2 edge case tests)

All 396 tests pass.

Author: jas88

CHANGELOG.md

@@ -12,12 +12,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - **DatabaseTypeRequest.Equals()**: Now uses type-specific equality semantics (Issue #19)
   - **decimal**: Compares only `CSharpType` and `Size` (precision/scale) - ignores `Width` and `Unicode`
-  - **string**: Compares `CSharpType`, `Width`, and `Unicode` - ignores `Size`
-  - **byte[]**: Compares `CSharpType` and `Width` - ignores `Size` and `Unicode`
+  - **string**: Compares `CSharpType`, explicit width (`_maxWidthForStrings`), and `Unicode` - ignores `Size`
+  - **byte[]**: Compares `CSharpType` and explicit width (`_maxWidthForStrings`) - ignores `Size` and `Unicode`
   - **Other types** (bool, int, long, DateTime, TimeSpan, Guid, etc.): Compares only `CSharpType`
   - Fixes round-trip equality when comparing guesser-created and SQL reverse-engineered types
-  - `GetHashCode()` updated to match new equality semantics for consistency
-  - Added 17 comprehensive tests covering all type-specific equality cases
+  - Compares backing field `_maxWidthForStrings` instead of computed `Width` property to avoid Size interference
+  - `GetHashCode()` updated to match new equality semantics for consistency and null-safety
+  - Added 19 comprehensive tests covering all type-specific equality cases and edge cases
 
 ## [2.0.1] - 2025-11-15
 

TypeGuesser/DatabaseTypeRequest.cs

@@ -182,7 +182,7 @@ public override int GetHashCode()
         }
 
         // For all other types, only hash the type
-        return CSharpType.GetHashCode();
+        return HashCode.Combine(CSharpType);
     }
 
     /// <summary>