Function js_fetch_error_callback

src/platforms/wasm/js_fetch.cpp.hpp:116–133

// C++ error callback function that JavaScript can call when fetch fails
extern "C" EMSCRIPTEN_KEEPALIVE void js_fetch_error_callback(u32 request_id, const char* error_message) {
    FL_WARN("Fetch error callback received for request " << request_id << ": " << error_message);
    
    auto callback_opt = getCallbackManager().takeCallback(request_id);
    if (callback_opt) {
        // Create an error response object using unified fl::response
        fl::net::http::Response response(0, "Network Error");
        fl::string error_content = "Fetch Error: ";
        error_content += error_message;
        response.set_body(error_content);

        (*callback_opt)(response);
    } else {
        FL_WARN("Warning: No pending callback found for fetch error request " << request_id);
    }
    // See note in js_fetch_success_callback above.
    fl::platforms::ICoroutineRuntime::instance().wakeWaiters();
}

void WasmFetchRequest::response(const FetchResponseCallback& callback) {
    FL_WARN("Starting JavaScript-based fetch request to: " << mUrl);