SDL2 image - IMG_Init() returns 0, with IMG_GetError() being empty

Question

I'm trying to load a png image with SDL2. However, even though the file exists and the renderer is created correctly, IMG_LoadTexture will only return a nullptr, for no apparent reason.

The function I'm using IMG_LoadTexture in looks like this, where texture is a SDL_Texture*:

void setTexture(const char* filePath) {
    // check if the specified file exists
    assert(utils::fileExists(filePath) && "Texture file does not exist!");

    // this should set the texture, but never succeeds
    texture = IMG_LoadTexture(Game::renderer, filePath);
    if (!texture) {
        // error handling, this is always true
    }
}

The assert passes, so the file was found. filePath looks something like "assets/texture.png". The Game::renderer is set beforehand and looks like this:

static SDL_Renderer* renderer; // in header

renderer = SDL_CreateRenderer(window, -1, 0); // in implementation
if(renderer) {
    SDL_SetRenderDrawColor(renderer, 100, 200, 255, 255);
} else {
// error handling and quit
}

However, despite IMG_LoadTexture not returning a proper SDL_Texture*, IMG_GetError() is simply empty, meaning

std::cout << IMG_GetError();

after calling IMG_LoadTexture does not output anything.

Seeing as I'm at a complete loss as to why this happens, I hope someone can help me here.

EDIT: As requested, here is a more complete, compilable version of the program that produces the same error.

I'm on Windows 10 Home 64-bit, using the 32-bit version of MingW-w64 to compile on C++17. My SDL2 version is 2.0.8, and my SDL2_image version is 2.0.3.

Here is the image I would like to load:

The image is contained inside a folder called assets in the original directory and the build directory. (I use CMake to remove the folder in the build directory pre-build and copy paste it post-build).

And here is the code:

#include <iostream>
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>

void quit(SDL_Window* window, SDL_Renderer* renderer) {
    SDL_DestroyWindow(window);
    SDL_DestroyRenderer(renderer);
    IMG_Quit();
    SDL_Quit();
    std::cout << "Quit Test." << std::endl;
}

int main(int argv, char** argc) {

    if (SDL_Init(SDL_INIT_EVERYTHING) == 0) {
        std::cout << "SDL initialized" << std::endl;
    } else {
        std::cerr << "Failed to initialize SDL" << std::endl;
        std::cerr << SDL_GetError() << std::endl;
        return 1;
    }
    auto window = SDL_CreateWindow("Test", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, 0);
    if (window) {
        std::cout << "Window created." << std::endl;
    } else {
        std::cerr << "Failed to create window." << std::endl;
        return 2;
    }

    auto initError = IMG_Init(IMG_INIT_PNG);
    if (initError == IMG_INIT_PNG) {
        std::cout << "SDL_image initialized" << std::endl;
    } else {
        std::cerr << "Failed to initialize SDL_image" << std::endl;
        std::cerr << "Return value: " << initError << std::endl;
        std::cerr << "Error flags: " << IMG_GetError() << std::endl;
        return 3;
    }

    auto renderer = SDL_CreateRenderer(window, -1, 0);
    if (renderer) {
        SDL_SetRenderDrawColor(renderer, 100, 200, 255, 255);
        std::cout << "Renderer created." << std::endl;
    } else {
        std::cerr << "Failed to create renderer." << std::endl;
        std::cerr << SDL_GetError() << std::endl;
        return 4;
    }

    auto texture = IMG_LoadTexture(renderer, "assets/player.png");
    if (!texture) {
        std::cerr << "Failed to load texture!" << std::endl;
        std::cerr << IMG_GetError() << std::endl;
        return 5;
    }

    quit(window, renderer);

    return 0;
}

Which outputs:

SDL initialized
Window created.
Failed to initialize SDL_image
Return value: 0
Error flags:

Process finished with exit code 3