The condition for raising onOutOfMemory is:
```
if (errno != ERANGE &&
    // On BSD and OSX, errno can be left at 0 instead of set to ERANGE
    errno != 0)
    onOutOfMemoryError();
```


The documentation of getpwam_r says any of the following errno codes could be set.
---
ERRORS
       0 or ENOENT or ESRCH or EBADF or EPERM or ...
              The given name or uid was not found.

       EINTR  A signal was caught; see signal(7).

       EIO    I/O error.

       EMFILE The per-process limit on the number of open file descriptors has been reached.

       ENFILE The system-wide limit on the total number of open files has been reached.

       ENOMEM Insufficient memory to allocate passwd structure.

       ERANGE Insufficient buffer space supplied.
---

The first set of errors should be checked, which breaks the loop before raising an OOM Exception (ENOENT is not an OOM issue).

Test that triggers failure.
```
assert(expandTilde("~Idontexist/hey") == "~Idontexist/hey");
```