[REGRESSION]: Errors inside route handler does not lead to unhandled rejections anymore

[mxschmitt]

Context:

• GOOD Playwright Version: 1.16.0
• BAD Playwright Version: 1.17.0
• Operating System: Linux
• Extra: [any specific details about your environment]

Code Snippet

Help us help you! Put down a short code snippet that illustrates your bug and
that we can run and debug locally. For example:

const playwright = require("playwright");

(async () => {
  const browser = await playwright.chromium.launch();
  const page = await browser.newPage();
  page.route("**/*", (route) => {
    throw new Error("foobar!")
  })
  await page.goto("https://example.com")
  await browser.close();
})();

Describe the bug

Expected: unhandled rejection with the error
Actual: nothing