This handles an empty string, and is called with that currently a lot

It can handle an empty string and is called with empty strings

These can handle empty strings, and are called with them.

These two functions examine their input string without checking if it is
zero length.  So, the assertion needs to change.  They aren't ever
called with an empty string.

This function takes a string with a beginning and ending pointer.  It
doesn't dereference if the string is empty, and returns the correct
value when empty, and does get called with empty strings.

These functions take a string argument with beginning and ending
positions.  They handle the case of an empty string properly, and the
documentation says they handle empty strings.

Calls in this file to these functions bypassed the macros, with no harm
currently done.  But it isn't good practice.

This internal function can handle empty strings, but it isn't ever
called with one so far, and it is better practice to not call it with an
empty string

This internal function looks problematic with regard to handling empty
strings, but it isn't ever called with one so far.  Change to catch such
calls that might get added in the future.

This internal function takes a string argument with beginning and
ending positions.  It handles the case of an empty string properly.

This internal function takes a string argument with beginning and
ending positions.  It is called all the time with an empty string,