This thread: "Can't happen" bugs discusses the exact same problem. It's a long thread, but the resolution seems to be to downgrade to version 1.42 of Compress::Zlib.

Alternatively, try installing the XS version of Scalar::Util.

Update: you can force the XS version to be built by using perl Makefile.PL -xs when building the distribution Scalar-List-Utils. However, it looks like the XS version should automatically be selected if your perl has access to a C compiler.