Reworked diagnostics, saves line positions in memory, instead of calculating later.

Upsilon/BaseTypes/UserData/ListUserData.cs

@@ -51,11 +51,9 @@ namespace Upsilon.BaseTypes.UserData
             }
             else
             {
-                var (i, pos) = diagnostics.ScriptString.GetLinePosition(span.Start);
-                var line = diagnostics.ScriptString.GetLine(i);
                 throw new ScriptRuntimeException(
                     $"Tried indexing a CSharp list with a value that's not an integer. Value: {scriptIndex.ToCSharpObject()}",
-                    i, pos, line);
+                    span, diagnostics.ScriptString.GetSpan(span));
             }
 
             index--;