fix: address architectural review findings from verification

- SymbolSerializer: use int.TryParse for FunctionType metadata fields
  to gracefully handle corrupted cache files instead of crashing
- TypeChecker: replace silent Unknown return with throw in
  CheckBytesLiteral (bytes type must be in BuiltinRegistry)
- OperatorValidator: add TODO(#559) for missing bytes comparison ops

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: antonsynd

src/Sharpy.Compiler/Project/SymbolSerializer.cs

@@ -873,9 +873,24 @@ private static void RegisterAll()
                         if (secondPipe >= 0)
                         {
                             var vStr = beforeO[(secondPipe + 1)..];
-                            paramsStr = beforeO[..secondPipe];
-                            optionalCount = int.Parse(oStr, System.Globalization.CultureInfo.InvariantCulture);
-                            variadicIndex = vStr == "-" ? null : int.Parse(vStr, System.Globalization.CultureInfo.InvariantCulture);
+                            // Use TryParse for resilience against corrupted cache files —
+                            // fall through to legacy format on failure rather than crashing.
+                            if (int.TryParse(oStr, System.Globalization.NumberStyles.Integer,
+                                    System.Globalization.CultureInfo.InvariantCulture, out var parsedOptional) &&
+                                (vStr == "-" || int.TryParse(vStr, System.Globalization.NumberStyles.Integer,
+                                    System.Globalization.CultureInfo.InvariantCulture, out _)))
+                            {
+                                paramsStr = beforeO[..secondPipe];
+                                optionalCount = parsedOptional;
+                                variadicIndex = vStr == "-"
+                                    ? null
+                                    : int.Parse(vStr, System.Globalization.CultureInfo.InvariantCulture);
+                            }
+                            else
+                            {
+                                // Malformed metadata — treat as legacy format
+                                paramsStr = innerStr;
+                            }
                         }
                         else
                         {

src/Sharpy.Compiler/Semantic/TypeChecker.Expressions.Literals.cs

@@ -391,9 +391,8 @@ private SemanticType CheckFStringLiteral(FStringLiteral fstr)
 
     private SemanticType CheckBytesLiteral(BytesLiteralExpression bytesLit)
     {
-        var bytesSymbol = _symbolTable.BuiltinRegistry.GetType(BuiltinNames.Bytes);
-        if (bytesSymbol == null)
-            return SemanticType.Unknown;
+        var bytesSymbol = _symbolTable.BuiltinRegistry.GetType(BuiltinNames.Bytes)
+            ?? throw new InvalidOperationException("bytes type must be registered in BuiltinRegistry");
         return new UserDefinedType { Name = bytesSymbol.Name, Symbol = bytesSymbol };
     }
 

src/Sharpy.Compiler/Semantic/Validation/OperatorValidator.cs

@@ -241,6 +241,7 @@ private bool SupportsOperator(SemanticType type, string dunderName)
         }
 
         // Bytes supports concatenation, repetition, equality, and containment
+        // TODO(#559): bytes comparison operators (<, <=, >, >=) not yet implemented
         if (type is UserDefinedType { Name: BuiltinNames.Bytes })
         {
             return dunderName is DunderNames.Add or DunderNames.Mul or DunderNames.Eq or DunderNames.Ne or DunderNames.Contains;