allow components off root, but only allow one or error

Common/Runtime.meta

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Common/Runtime/CommonRuntime.asmdef

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Common/Runtime/ComponentHelper.cs

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+using UnityEngine;
+
+namespace gay.lilyy.Common
+{
+    public static class ComponentHelper
+    {
+        /// <summary>
+        /// Searches for a component in children of the root GameObject.
+        /// Returns null if no component is found.
+        /// Logs an error and returns null if multiple components are found.
+        /// </summary>
+        /// <typeparam name="T">The component type to search for</typeparam>
+        /// <param name="root">The root GameObject to search in</param>
+        /// <returns>The component if exactly one is found, null otherwise</returns>
+        public static T? GetComponentInChildrenWithError<T>(GameObject root) where T : Component
+        {
+            if (root == null) return null;
+
+            T[] components = root.GetComponentsInChildren<T>(true);
+            if (components.Length == 0)
+            {
+                return null;
+            }
+            if (components.Length > 1)
+            {
+                Debug.LogError($"Multiple {typeof(T).Name} components found in children of {root.name}. Only one is allowed.");
+                return null;
+            }
+            return components[0];
+        }
+
+        /// <summary>
+        /// Searches for a component in children of the root Transform.
+        /// Returns null if no component is found.
+        /// Logs an error and returns null if multiple components are found.
+        /// </summary>
+        /// <typeparam name="T">The component type to search for</typeparam>
+        /// <param name="root">The root Transform to search in</param>
+        /// <returns>The component if exactly one is found, null otherwise</returns>
+        public static T? GetComponentInChildrenWithError<T>(Transform root) where T : Component
+        {
+            if (root == null) return null;
+
+            T[] components = root.GetComponentsInChildren<T>(true);
+            if (components.Length == 0)
+            {
+                return null;
+            }
+            if (components.Length > 1)
+            {
+                Debug.LogError($"Multiple {typeof(T).Name} components found in children of {root.name}. Only one is allowed.");
+                return null;
+            }
+            return components[0];
+        }
+    }
+}
+

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