can't access window.swaggerUi inside injected JS code

[wojciech-zur]

I have a backend in .NET 8, where I InjectJavascript like this:

var app = builder.Build();
app.UseDefaultFiles();
app.UseStaticFiles();
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI(c =>
    {
        // Add custom JavaScript to the Swagger UI
        c.InjectJavascript("/customSwaggerLogin.js");
    });
}

my customSwaggerLogin.js content is:

document.ready = function () {
    // Add login button
    const authButton = document.createElement('button');
    authButton.innerText = 'Log In and Get Token';
    authButton.onclick = async function () {
        // Login data
        const loginData = {
            Username: 'login',
            Password: 'pass'
        };
        try {
            const response = await fetch('https://localhost:7031/Auth/login', {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify(loginData)
            });
            const data = await response.json();
            if (data.token) {
                // Set JWT token in Swagger UI
                window.swaggerUi.api.clientAuthorizations.add('jwtAuth', new SwaggerClient.ApiKeyAuthorization('Authorization', `Bearer ${data.token}`, 'header'));
                alert('Logged in successfully');
            } else {
                alert('Login failed');
            }
        } catch (error) {
            console.error('Login error', error);
            alert('Login error');
        }
    };

    // Add the button to Swagger UI
    var r1 = document.querySelector('.swagger-ui .topbar').appendChild(authButton);
};

The code properly fetches JWT token, but it crashes here:

window.swaggerUi.api.clientAuthorizations.add('jwtAuth', new SwaggerClient.ApiKeyAuthorization('Authorization', `Bearer ${data.token}`, 'header'));

telling me that window.swaggerUi is undefined. I will be glad for any hint with this issue.