Slightly optimize SimpleMetaValueSelector by only invoking the selection strategy if there is a selection to be made

common/src/main/java/me/lucko/luckperms/common/cacheddata/type/SimpleMetaValueSelector.java

@@ -43,8 +43,15 @@ public class SimpleMetaValueSelector implements MetaValueSelector {
 
     @Override
     public @NonNull String selectValue(@NonNull String key, @NonNull List<String> values) {
+        switch (values.size()) {
+            case 0:
+                throw new IllegalArgumentException("values is empty");
+            case 1:
+                return values.get(0);
+            default:
                 return this.strategies.getOrDefault(key, this.defaultStrategy).select(values);
         }
+    }
 
     public enum Strategy {
         INHERITANCE {