chore(typescript): resolve errors

[liamdebeasi]

Two errors appear when editing files:

Object is possibly 'undefined'.

    L125:   icon.name = 'trash';
    L126:   await page.waitForChanges();

and

Cannot find module 'puppeteer' or its
           corresponding type declarations.

      L8:  setup(): Promise<void>;
      L9:  ppeteerPage(): Promise<import("puppeteer").Page>;
     L10:  closeOpenPages(): Promise<void>;

This PR fixes both errors.