> There should be more strict handling of invalid input so they result in actual exceptions being thrown instead of output that can be exploited in incorrect/undocumented ways.
It's trivial to turn all notices/warnings/errors into exceptions in PHP (it even provides an exception class for it, ErrorException). PHP is multi-paradigm and supports many different ways of handling errors and warnings.
> This is a bug in the varied way in which PHP returns output based on invalid input. Some functions return 0, some functions return NULL, some functions return FALSE and it seems as if it is all done arbitrarily.
This change was to make the output of functions consistent based on invalid input. It's specifically addressing this point. It's also the very first point listed in the migration documentation