Java EE encounters a strange error during operation

1.Server environment 1.1JDK1.8 1.2Tomcat9 1.3Ubuntu 20.04.6 LTS 2 Problem screenshot 2.1.Screenshot of the API call system error log is shown in Figure 1

http://static.haou8.cn/question_1.png Figure 1 error log of system 2.2 Erroneous program code is shown in Figure 2

http://static.haou8.cn/question_2.png Figure 2 error of program

3 Questions 3.1 Description of problem In Figure 2, there are no issues with the program code on line 372 (checking if JSON is empty) and line 376 (executing normally if JSON is not empty), but there is an error on line 392 (JSON object is empty). Could you please tell me the reason for the error. 3.2 Cause of program exception The JSON object is released when the program executes to line 392.

3.3 Problem? Please analyze the reasons for this issue from the perspective of server operation and maintenance。