Fixed DefaultTypeInspector concurrency issue. (#8608)

Author: michaelstaib

src/HotChocolate/Core/src/Types/Types/Descriptors/Conventions/DefaultTypeInspector.cs

@@ -30,7 +30,7 @@ public class DefaultTypeInspector(bool ignoreRequiredAttribute = false) : Conven
     private const string _clone = "<Clone>$";
 
     private readonly TypeCache _typeCache = new();
-    private readonly Dictionary<MemberInfo, ExtendedMethodInfo> _methods = new();
+    private readonly ConcurrentDictionary<MethodInfo, ExtendedMethodInfo> _methods = new();
     private readonly ConcurrentDictionary<(Type, bool, bool), MemberInfo[]> _memberCache = new();
 
     /// <summary>
@@ -181,13 +181,7 @@ public virtual IExtendedType GetArgumentType(
     private IExtendedType GetArgumentTypeInternal(ParameterInfo parameter)
     {
         var method = (MethodInfo)parameter.Member;
-
-        if (!_methods.TryGetValue(method, out var info))
-        {
-            info = ExtendedType.FromMethod(method, _typeCache);
-            _methods[method] = info;
-        }
-
+        var info = _methods.GetOrAdd(method, static (m, c) => ExtendedType.FromMethod(m, c), _typeCache);
         return info.ParameterTypes[parameter];
     }