Handmade Hero day 4 linker error

#include <windows.h>

#define internal static
#define local_persist static
#define global_variable static

// TODO global for now
global_variable bool Running;


global_variable BITMAPINFO BitmapInfo;
global_variable void *BitmapMemory;
global_variable int BitmapWidth;
global_variable int BitmapHeight;

internal void
Win32ResizeDIBSection(int Width, int Height){

    if (BitmapMemory){
        VirtualFree(BitmapMemory, 0, MEM_RELEASE);
    }

    // see global above; BITMAPINFO BitmapInfo;

    BitmapWidth = Width;
    BitmapHeight = Height;

    BitmapInfo.bmiHeader.biSize = sizeof(BitmapInfo.bmiHeader);
    BitmapInfo.bmiHeader.biWidth = BitmapWidth;
    BitmapInfo.bmiHeader.biHeight = -BitmapHeight; //biHeight starts from bottom, so Height must be flipped
    BitmapInfo.bmiHeader.biPlanes = 1;
    BitmapInfo.bmiHeader.biBitCount = 32;
    BitmapInfo.bmiHeader.biCompression = BI_RGB;

    int bytesPerPixel = 4;
    int BitmapMemorySize = bytesPerPixel * (BitmapWidth*BitmapHeight);
    BitmapMemory = VirtualAlloc(0, BitmapMemorySize, MEM_COMMIT, PAGE_READWRITE);
}

internal void
Win32UpdateWindow(HDC DeviceContext, RECT * WindowRect, int X, int Y, int Width, int Height){

    int WindowWidth = WindowRect->right - WindowRect->left;
    int WindowHeight = WindowRect->bottom - WindowRect->top;

    StretchDIBits(DeviceContext,
        0, 0,BitmapWidth, BitmapHeight,
        0, 0, WindowWidth, WindowHeight,
        BitmapMemory,
        &BitmapInfo,
        DIB_RGB_COLORS, SRCCOPY);
}

LRESULT CALLBACK
Win32MainWindowCallback(HWND Window, UINT Message, WPARAM WParam, LPARAM LParam){

    LRESULT Result = 0;

    switch (Message){
        case WM_SIZE:
        {
            RECT ClientRect;
            GetClientRect(Window, &ClientRect);
            int Width = ClientRect.right - ClientRect.left;
            int Height = ClientRect.bottom - ClientRect.top;
            Win32ResizeDIBSection(Width, Height);
            OutputDebugStringA("WM_SIZE \n");
        }break;
        case WM_DESTROY:
        {
            Running = false;
            OutputDebugStringA("WM_DESTROY \n");
        }break;
        case WM_CLOSE:
        {
            Running = false;
        }break;
        case WM_ACTIVATEAPP:
        {
            OutputDebugStringA("WM_ACTIVATE \n");
        }break;
        case WM_PAINT:
        {

            PAINTSTRUCT Paint;
            HDC DeviceContext = BeginPaint(Window, &Paint);
            int X = Paint.rcPaint.left;
            int Y = Paint.rcPaint.top;
            int Width = Paint.rcPaint.right - Paint.rcPaint.left;
            int Height = Paint.rcPaint.bottom - Paint.rcPaint.top;

            RECT ClientRect;
            GetClientRect(Window, &ClientRect);

            Win32UpdateWindow(DeviceContext, &ClientRect, X, Y, Width, Height);
            local_persist DWORD Operation = WHITENESS;
            PatBlt(DeviceContext, X, Y, Width, Height, Operation);
            if (Operation == WHITENESS)
            {
                Operation = BLACKNESS;
            }
            else
            {
                Operation = WHITENESS;
            }

            EndPaint(Window, &Paint);
        }break;
        default:
        {
            OutputDebugStringA("Default \n");
            Result = DefWindowProc(Window, Message, WParam, LParam);
        }break;
    }
    return(Result);
}

int CALLBACK
Win32WinMain(HINSTANCE Instance, HINSTANCE PrevInstance, LPSTR CommandLine, int ShowCode){

    WNDCLASS WindowClass = {};
        WindowClass.style = CS_OWNDC|CS_HREDRAW|CS_VREDRAW;
        WindowClass.lpfnWndProc = Win32MainWindowCallback;
//      WindowClass.cbClsExtra = ;
//      WindowClass.cbWndExtra = ;
        WindowClass.hInstance = Instance;
//      WindowClass.hIcon;
//      WindowClass.hCursor;
//      WindowClass.hbrBackground;
//      WindowClass.lpszMenuName;
        WindowClass.lpszClassName = (LPCWSTR)L"HandmadeHeroWindowClass";

        if (RegisterClass(&WindowClass)){
            HWND WindowHandle = CreateWindowEx(
                0,
                WindowClass.lpszClassName,
                (LPCWSTR)L"Handmade Hero",
                WS_OVERLAPPEDWINDOW | WS_VISIBLE,
                CW_USEDEFAULT,
                CW_USEDEFAULT,
                CW_USEDEFAULT,
                CW_USEDEFAULT,
                0,
                0,
                Instance,
                0);
            if (WindowHandle){
                    while(Running){
                        MSG Message;
                        BOOL MessageResult = GetMessage(&Message, 0, 0, 0);
                        if (MessageResult > 0){
                            TranslateMessage(&Message);
                            DispatchMessage(&Message);
                        }
                        else{
                            break;
                        }

                    }

            }
            else{

            }
        }
        else{
        }

    MessageBox(0, (LPCWSTR)L"This is Handmade Hero", (LPCWSTR)L"Handmade Hero", MB_OK | MB_ICONINFORMATION);
    return 0;
}