Fix intermittent docId unit test failure

[timvandermeij]

The TEST-UNEXPECTED-FAIL | checks that docIds are unique and increasing | in chrome | Expected 9 to be less than 0 unit test failed in a recent test run in #13837 (comment), but also locally once for me. Perhaps this goes wrong because the test depends on state that might be mutated if the tests are shuffled?

/cc @Snuffleupagus since this unit test was added in b18620a

[timvandermeij]

Ah, maybe the problem is that the + needs to be inside the paretheses at b18620a#diff-bc84ed767f5905bdf8c544c715c08e9b751e7bb1db16c8182d9de515b56bc4b6R400 since otherwise it only matches one digit in case the number is 10 for example?

[Snuffleupagus]

Whoops, sorry about this and thanks for pin-pointing the problem in #13838 (comment).