Fixed race condition in Cache

Core/Cache.cs

@@ -22,8 +22,13 @@ namespace FLocal.Core {
 					}
 				}
 			}
+			lock(id) {
+				if(this.cache.ContainsKey(id)) {
 					return this.cache[id];
 				}
+			}
+			return this.get(id, getter);
+		}
 
 		public void delete(object id) {
 			lock(id) {