update fix history chatroom crash bug

Author: huangminlinux

ios/RCTJMessageModule/RCTJMessageModule.m

@@ -830,6 +830,11 @@ - (JMSGOptionalContent *)convertDicToJMSGOptionalContent:(NSDictionary *)dic {
       return [message messageToDictionary];
     }];
 
+    if (!messageArr) {
+      successCallback(@[@[]]);
+      return;
+    }
+    
     successCallback(@[messageDicArr]);
   }];
 }