Memcheck showing issues for external errors and Leaks.

On running memcheck for the following code:

Code:

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#include <QApplication>
#include <QPushButton>
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QWidget window;
 
    window.resize(600, 600);
    QPushButton button(&window);
    window.show();
 
    return app.exec();
}

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These errors are obtained on checking the external error flag for memcheck:

Code:

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Syscall param writev(vector[...]) points to uninitialised byte(s)
Address 0xcc7be09 is 4,537 bytes inside a block of size 21,152 alloc'd  1: calloc in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so
Uninitialised value was created by a stack allocation  1: non-virtual thunk to QXcbWindow::setVisible(bool) in /home/captaindavinci/Qt/5.8/gcc_64/lib/libQt5XcbQpa.so.5.8.0
 
Location is main.cpp: 7
and so on..

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And so is there a question here (and so on)?