Win32 blank window c/c++

#include <iostream>
#include <Windows.h>

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);

int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, PWSTR pCmdLine, int nCmdShow) {
    LPCWSTR className = L"REghZy Frame Control";
    LPCWSTR winTitle = L"Frame Control";

    WNDCLASSW wc = {};
    wc.lpfnWndProc = WindowProc;
    wc.hInstance = hInstance;
    wc.lpszClassName = className;

    if (!RegisterClassW(&wc)) {
        printf("Failed to register class");
        MessageBoxW(NULL, L"Failed to register application class", L"App init failure - instance", NULL);
        return 0;
    }

    HWND hwnd = CreateWindowExW(
        0,                    // Optional window styles.
        className,            // Window class
        winTitle,             // Window titlebar
        WS_OVERLAPPEDWINDOW,  // Window style

        // Size and position
        CW_USEDEFAULT, // x
        CW_USEDEFAULT, // y
        500,           // w
        500,           // h

        NULL,       // Parent window
        NULL,       // Menu
        hInstance,  // Instance handle
        NULL        // Additional application data
    );

    if (!hwnd) {
        printf("Failed to register class");
        MessageBoxW(NULL, L"Failed to create application main window", L"App init failure - window", NULL);
        return 0;
    }

    ShowWindow(hwnd, nCmdShow);

    // Run the message loop.

    MSG msg = { };
    while (GetMessage(&msg, NULL, 0, 0) > 0) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return 0;
}

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
    switch (uMsg) {
        case WM_DESTROY: {
            PostQuitMessage(0);
            return 0;
        }

        case WM_PAINT: {
            PAINTSTRUCT ps;
            HDC hdc = BeginPaint(hwnd, &ps);

            // All painting occurs here, between BeginPaint and EndPaint.

            FillRect(hdc, &ps.rcPaint, (HBRUSH)(COLOR_WINDOW + 1));

            EndPaint(hwnd, &ps);
        }

        return 0;
    }

    return DefWindowProc(hwnd, uMsg, wParam, lParam);
}