Texture won't appear if not created directly before the draw command

I wrote a function to draw a rectangle and I want to add a texture. However, OpenGL can't apply it if it was initialized not in drawing function.

class Material {
public:

    Material(const char* filename) {
    
        int width, height, channels;
        unsigned char* data = stbi_load(filename, &width, &height, &channels, STBI_rgb_alpha);
        glEnable(GL_TEXTURE_2D);

        glGenTextures(1, &texture);
        glBindTexture(GL_TEXTURE_2D, texture);
    
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

        stbi_image_free(data);
    }

    ~Material() { release(); }

    Material(const Material &) = delete;
    Material &operator=(const Material &) = delete;

    Material(Material &&other) : texture(other.texture) {
        other.texture = 0; 
    }

    Material &operator=(Material &&other) {
        if(this != &other) {
            release();
            std::swap(texture, other.texture);
        }
    }

    GLuint texture = 0; 

private:

    void release() {
        glDeleteTextures(1, &texture);
        texture = 0;
    }
};

class SRender {
public:

    Material* mat = new Material("01.png");
    
    void drawRect () const;
};

float vertex[] = {0,0,0, 0,1,0, 1,1,0, 1,0,0};
float texCord[] = {0,0, 0,1, 1,1, 1,0};

void SRender::drawRect() const {
    
    //Material* mat2 = new Material("01.png");

    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, mat->texture);

    glColor3f(1, 1, 1);
    glPushMatrix();
    glEnableClientState(GL_VERTEX_ARRAY);
    glEnableClientState(GL_TEXTURE_COORD_ARRAY);

    glVertexPointer(3, GL_FLOAT, 0, vertex);
    glTexCoordPointer(2, GL_FLOAT, 0, texCord);
    
    glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

    glDisableClientState(GL_VERTEX_ARRAY);
    glDisableClientState(GL_TEXTURE_COORD_ARRAY);

    glPopMatrix();
}

#include <windows.h>
#include <gl/gl.h>

#pragma comment(lib, "opengl32.lib")

#define STB_IMAGE_IMPLEMENTATION    
#include "stb_image.h"

LRESULT CALLBACK WindowProc(HWND, UINT, WPARAM, LPARAM);
void EnableOpenGL(HWND hwnd, HDC*, HGLRC*);
void DisableOpenGL(HWND, HDC, HGLRC);


int WINAPI WinMain(HINSTANCE hInstance,
    HINSTANCE hPrevInstance,
    LPSTR lpCmdLine,
    int nCmdShow)
{
    WNDCLASSEX wcex;
    HWND hwnd;
    HDC hDC;
    HGLRC hRC;
    MSG msg;
    BOOL bQuit = FALSE;

    wcex.cbSize = sizeof(WNDCLASSEX);
    wcex.style = CS_OWNDC;
    wcex.lpfnWndProc = WindowProc;
    wcex.cbClsExtra = 0;
    wcex.cbWndExtra = 0;
    wcex.hInstance = hInstance;
    wcex.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH);
    wcex.lpszMenuName = NULL;
    wcex.lpszClassName = "GLSample";
    wcex.hIconSm = LoadIcon(NULL, IDI_APPLICATION);;


    if (!RegisterClassEx(&wcex))
        return 0;


    SRender render;


    hwnd = CreateWindowEx(0,
        "GLSample",
        "OpenGL Sample",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        256,
        256,
        NULL,
        NULL,
        hInstance,
        NULL);

    ShowWindow(hwnd, nCmdShow);

    EnableOpenGL(hwnd, &hDC, &hRC);

    while (!bQuit)
    {
        if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
        {
            if (msg.message == WM_QUIT)
            {
                bQuit = TRUE;
            }
            else
            {
                TranslateMessage(&msg);
                DispatchMessage(&msg);
            }
        }
        else
        {
            glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
            glClear(GL_COLOR_BUFFER_BIT);

            glPushMatrix();

            render.drawRect();

            glPopMatrix();

            SwapBuffers(hDC);

            Sleep(1);
        }
    }

    DisableOpenGL(hwnd, hDC, hRC);

    DestroyWindow(hwnd);

    return msg.wParam;
}

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

    case WM_DESTROY:
        return 0;

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

    return 0;
}

void EnableOpenGL(HWND hwnd, HDC* hDC, HGLRC* hRC)
{
    PIXELFORMATDESCRIPTOR pfd;

    int iFormat;

    *hDC = GetDC(hwnd);

    ZeroMemory(&pfd, sizeof(pfd));

    pfd.nSize = sizeof(pfd);
    pfd.nVersion = 1;
    pfd.dwFlags = PFD_DRAW_TO_WINDOW |
        PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER;
    pfd.iPixelType = PFD_TYPE_RGBA;
    pfd.cColorBits = 24;
    pfd.cDepthBits = 16;
    pfd.iLayerType = PFD_MAIN_PLANE;

    iFormat = ChoosePixelFormat(*hDC, &pfd);

    SetPixelFormat(*hDC, iFormat, &pfd);

    *hRC = wglCreateContext(*hDC);

    wglMakeCurrent(*hDC, *hRC);
}

void DisableOpenGL(HWND hwnd, HDC hDC, HGLRC hRC)
{
    wglMakeCurrent(NULL, NULL);
    wglDeleteContext(hRC);
    ReleaseDC(hwnd, hDC);
}

If I use mat in glBindTexture, it draws a white rectangle, but if I use mat2 it works. I don't want to initialize it every time when I draw something. What is going wrong here?

The SRender object is created before the OpenGL window and context are created. Since no OpenGL API function works without a current OpenGL context, the texture creation fails. The SRender object must be created after the OpenGL context has been made current with EnableOpenGL.

// SRender render;                <--- DELETE

hwnd = CreateWindowEx(...);
ShowWindow(hwnd, nCmdShow);
EnableOpenGL(hwnd, &hDC, &hRC);

SRender render;                 // <--- INSERT