The old implementation of case conversion types can handle several
values which are not strings, but the signature did not reflect this.
The new one reports errors when falsy non-string inputs are given to
the pipe (such as `false` or `0`) and has a new signature which
instead reflects the behaviour on `null` and `undefined`.
Fixes#36259
BREAKING CHANGE:
The case conversion pipes no longer let falsy values through. They now
map both `null` and `undefined` to `null` and raise an exception on
invalid input (`0`, `false`, `NaN`) just like most "common pipes". If
your code required falsy values to pass through, you need to handle them
explicitly.
PR Close#37447
c7d5555dfb