Problems with cypress 7.5.0 & @cyprss/react and 'uncaught:exception' handling

[glomotion]

Current behavior

REPRO: https://github.com/glomotion/cypress-bug-repro

When running headless tests WITH coverage enabled, cypress errors out (npm run test)

However when running headed or with coverage DISABLED, cypress tests pass as they should (npm run test:fast or npm run test:watch)

Desired behavior

Tests should pass in all modes or fail in all modes 🤪 🤷

Test code to reproduce

REPRO: https://github.com/glomotion/cypress-bug-repro

NOTE: these tests are using 'uncaught:exception' to catch runtime errors, and assert that they are happening correctly. EG:

before(() => {
    Cypress.on('uncaught:exception', () => {
      // returning false here prevents Cypress from
      // failing the test
      return false;
    });
  });

it('should throw error, when a fragment is supplied as children', done => {
    cy.on('uncaught:exception', err => {
      expect(err.message).to.include(ERROR_TEXT);
      done();
      return false;
    });
    mount(
      <AppHeaderBarNavItem testId="nav1">
        <>moo</>
      </AppHeaderBarNavItem>,
    );
  });

Versions

MacOS: 11.4 (20F71)
MacBook Pro (15-inch, 2019)

  "@cypress/code-coverage": "^3.9.6",
  "@cypress/react": "^5.9.1",
  "@cypress/webpack-dev-server": "^1.3.1",
  "cypress": "^7.5.0",
  "cypress-real-events": "^1.5.0",

[bahmutov]

I looked at the situation, something is wrong because when the error is thrown Cypress CT tries to mount the component again causing the problem. You can find my simplified test in https://github.com/bahmutov/double-error-bug

• npm install
• npm run test:watch

I am printing the log message before throwing the error

if (
    typeof children === 'string' ||
    isReactFragment(children) ||
    !isChildReactComponent(children)
  ) {
    console.error('App throwing an error')
    throw Error(ERROR_TEXT);
  }

I see the double log message in the console, which is incorrect

[bahmutov]

By the way, we have error message tests for E2E here https://github.com/cypress-io/cypress-example-recipes/tree/master/examples/fundamentals__errors

[lmiller1990]

I think we fixed error propagation as part of CT Stack Traces: #23916

Should be 💯 now.