LibraryCallKit::inline_string_copy() and LibraryCallKit::inline_string_getCharsU() use LibraryCallKit::tightly_coupled_allocation() to skip zeroing the array elements of a tightly coupled array allocation. However, the intrinsics do not take care of zeroing remaining array elements not affected by the intrinsic operation.
Currently, this is not a problem because all (String API internal) usages of the intrinsics that have a tightly coupled allocation make sure that the entire array is initialized. However, we should fix this to avoid potential bugs.