a confusing behaviour in c++ extension

Issue Type: Bug

I worte a program which applies for memory twice.when I debug it in vscode,it reported an exeption at the seccond application for memory.But when I run this compiled executive file in the work directory,it behaved right.Here is the function I used twice to applying for memory:
void init_list(struct arraylist * list){
list->list = (int *) malloc(5 * (sizeof 1));
if(list->list == NULL){
printf("内存分配错误\n");
}
list->length = 0;
list->list_size = 5 * (sizeof 1);
}

Extension version: 0.22.1
VS Code version: Code 1.32.3 (a3db5be9b5c6ba46bb7555ec5d60178ecc2eaae4, 2019-03-14T23:43:35.476Z)
OS version: Windows_NT x64 10.0.17763