fix: prevent ArgumentOutOfRangeException in XRefHrefFixer.FixPackage

P0.3 — MethodNameRegex requires '(' in the name to match. When it does
not match, Groups[1].Value is "" causing name.Substring(0, 0) = "" and
uid.IndexOf("") == 0, so uid.Substring(0, -1) threw. Fix: fall back to
using name directly when the regex does not match.

P0.2 — IndexOf returns -1 when methodName or name is not present in uid,
making Substring(0, -2) throw. Fix: guard both call sites; when the name
is absent from uid, return a best-effort href using the uid directly with
non-word characters replaced by underscores.

https://claude.ai/code/session_01WNaTJnpDwNjqyfL1uhYqJ4

Author: claude

UnityXrefMaps/XRefHrefFixer.cs

@@ -39,15 +39,32 @@ private static string FixPackage(string apiUrl, string name, string type, string
                 case "M":
                     Match methodNameMatch = MethodNameRegex().Match(name);
 
-                    string methodName = name.Substring(0, methodNameMatch.Groups[1].Value.Length);
+                    // P0.3: regex requires '(' — fall back to the full name when it is absent
+                    string methodName = methodNameMatch.Success
+                        ? name.Substring(0, methodNameMatch.Groups[1].Value.Length)
+                        : name;
 
-                    classFullName = uid.Substring(0, uid.IndexOf(methodName) - 1);
+                    // P0.2: IndexOf returns -1 when methodName is not present in uid
+                    int methodIdx = uid.IndexOf(methodName);
+                    if (methodIdx < 0)
+                    {
+                        return $"{apiUrl}{NonWordCharRegex().Replace(uid, "_")}.html";
+                    }
+
+                    classFullName = uid.Substring(0, methodIdx - 1);
 
                     return $"{apiUrl}{classFullName}.html#{NonWordCharRegex().Replace(uid, "_")}";
                 case "P":
                 case "F":
                 default:
-                    classFullName = uid.Substring(0, uid.IndexOf(name) - 1);
+                    // P0.2: IndexOf returns -1 when name is not present in uid
+                    int nameIdx = uid.IndexOf(name);
+                    if (nameIdx < 0)
+                    {
+                        return $"{apiUrl}{NonWordCharRegex().Replace(uid, "_")}.html";
+                    }
+
+                    classFullName = uid.Substring(0, nameIdx - 1);
 
                     return $"{apiUrl}{classFullName}.html#{NonWordCharRegex().Replace(uid, "_")}";
             }