GMock SetArrayArgument double free or corruption

Question

Edit: I solved the double free error myself, however the question (question 1) why it behaves differently from command line and inside CLion still remains...

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I am trying to use gmock and gtest. I want to mock a function that takes a pointer as an argument and fills it with content. My mock class has the following functions:

//MockUdpServer class
MOCK_METHOD(int, receive_msg_impl, (unsigned char *buf, int sec, int usec));

virtual int receive_msg(unsigned char *buf, int sec = -1, int usec = -1) override {
        return receive_msg_impl(buf, sec, usec);
}

My test code looks as follows:

TEST(Action, ref) {
    MockUdpServer mock_server;

    unsigned char test[]={0x0, 0x61}

    EXPECT_CALL(mock_server, receive_msg_impl)
            .WillOnce(SetArrayArgument<0>(test, test+2));

    unsigned char a[256];
    mock_server.receive_msg(a);
}

Now after the call to receive_msg I expect array a to have the content of test. When I execute this in CLion a just has random content. When I build it separately with cmake and run it, I get the error message

double free or corruption (out)
Aborted (core dumped)

There are two things that confuse me:

1. Why is there a difference between running inside CLion and running it from command line? I guess it could be some compiler flags?
2. (This setup does work under different circumstances, e.g. I have another object, which takes the MockUdpServer and internally calls receive_msg on it. This call is successful. Why does it not work directly in the test itself? Answer: In the other test cases I used DoAll and specified both the return value and the array content.)

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Edit: Apparently the test code has to specify the return value, even though it is not being used. The following code does not produce any error:

TEST(Action, ref) {
    MockUdpServer mock_server;

    unsigned char test[]={0x0, 0x61}

    EXPECT_CALL(mock_server, receive_msg_impl)
            .WillOnce(DoAll(
                   SetArrayArgument<0>(test, test+2),
                   Return(2)));

    unsigned char a[256];
    mock_server.receive_msg(a);
}