Debug error overlap with valid tokens

csharp_mod/Formatter.cs

@@ -170,18 +170,21 @@ public class SlangFormatter : ICodeFormatter
             if (line is null)
                 continue;
 
-            // 1. Get base syntax tokens
+            // 1. Get base syntax tokens, converting to a dictionary for ease in deduping error tokens
-            var allTokens = Marshal.TokenizeLine(line.Text);
+            var allTokensDict = Marshal.TokenizeLine(line.Text).ToDictionary((k) => k.Column);
 
-            // 2. Overlay error tokens if diagnostics exist for this line
+            // 2. Replace valid tokens with error tokens if present
             if (dict.ContainsKey(lineIndex))
             {
                 foreach (var lineDiagnostic in dict[lineIndex])
                 {
-                    allTokens.Add(
+                    var column = Math.Abs((int)lineDiagnostic.Range.StartCol);
-                        new SemanticToken(
+                    L.Info(
+                        $"Overwriting token at L:{lineIndex} C:{column} - Range:{lineDiagnostic.Range.EndCol - lineDiagnostic.Range.StartCol}"
+                    );
+                    allTokensDict[column] = new SemanticToken(
                         line: (int)lineIndex,
-                            column: Math.Abs((int)lineDiagnostic.Range.StartCol),
+                        column,
                         length: Math.Abs(
                             (int)(lineDiagnostic.Range.EndCol - lineDiagnostic.Range.StartCol)
                         ),
@@ -189,15 +192,15 @@ public class SlangFormatter : ICodeFormatter
                         style: ICodeFormatter.ColorError,
                         data: lineDiagnostic.Message,
                         isError: true
-                        )
                     );
                 }
             }
 
+            var allTokens = allTokensDict.Values.ToList();
+
             // 3. Update the line (this clears existing tokens and uses the list we just built)
             line.Update(allTokens);
 
-            // 4. CRITICAL FIX: Re-attach metadata that Update() dropped
             ReattachMetadata(line, allTokens);
         }