return NULL from psl_load_file() if the file could not be read.
return NULL from psl_load_file() if the file could not be read.

dkg/libpsl,dago/libpsl,darnir/libpsl,rockdaboot/libpsl,darnir/libpsl,dago/libpsl,darnir/libpsl,dago/libpsl,rockdaboot/libpsl,rockdaboot/libpsl,dkg/libpsl