window.opener is null in oauth2-redirect.html

I have read all previously closed issues relating to this subject, but most answers are not very detailed.

I am using @nestjs/swagger for my swagger-ui.

Here is what my setup looks like

// I had to turn of CSP briefly, as the scripts on oauth2-redirect.html were not allowed to execute for some reason
  app.use(
    helmet({
      contentSecurityPolicy: false,
    }),
  );

  const config = new DocumentBuilder()
    .setTitle('ReNeuro API')
    .setVersion('1.0')
    .addOAuth2({
      type: 'oauth2',
      flows: {
        authorizationCode: {
          authorizationUrl: process.env.SWAGGER_AUTHORIZATION_URL,
          scopes: [],
        },
      },
    })
    .build();

  SwaggerModule.setup('docs', app, document, {
    swaggerOptions: {
      oauth: {
        clientId: process.env.SWAGGER_COGNITO_CLIENT_ID,
        clientSecret: process.env.SWAGGER_COGNITO_CLIENT_SECRET,
      },
    },
  });

When I click "Authorize"

I can login via my provider (cognito), and it successfully puts the code into the URL, but my oauth2-redirect.html page throws the following error:

Uncaught TypeError: Cannot read properties of null (reading 'swaggerUIRedirectOauth2')
    at run (oauth2-redirect.html)

I have tested on Firefox and Chrome, same issue.

Any help with this would be really appreciated

Start with oauth2-redirect.html and reproduce the Authorize flow in Chrome or Firefox using the configuration shown. Inspect the run path around the window.opener access and verify that the returned code is handled without the null-reference error; the issue is resolved when the redirect completes successfully.