Symfony version(s) affected: 3.4.39

Description
After upgrading to 3.4.40 I am receiving a preg_match error within our unit tests on TimeType. This issue has been introduced within #36020

Even though this issue would probably have been created due to assumptions in our code base, we would expect that the backwards compatibility promise would ensure the working of this code through patch updates.

How to reproduce
submit a form where the data of a TimeType is of type DateTme

Possible Solution
Make sure the second argument is a string when using preg_match or skip logic if data is an object instead of a string

Additional context