Multi-byte chars count as more than one char

[pebo]

Describe the bug
When using a maxLength constraint on a string multi-byte chars such as ö is counted as more than one length unit (two for ö).

To Reproduce
Edit the test testing maxLength: 10

  it('should return 200 if short b-name is fetched', async () =>
    request(allErrorsApp)
      .get(`${allErrorsApp.basePath}/persons?bname=Boböööö`)
      .expect(200));

Actual behavior
Test fails.

Expected behavior
The ö chars should count as one length unit so the string Boböööö should have length 7.

Examples and context