suspicious code in convert_xml_string_to_value()

[Ben Pfaff]

The "Clang" static analyzer pointed out that
convert_xml_string_to_value(), in gnumeric-reader.c, contains
some suspicious code.  In particular, it checks at the top
whether the 'text' parameter is null, but both branches of the
"if" then depend on 'text' being nonnull.  I think that this must
be a bug, but I do not know what the solution should be.

I'm happy to file this as a bug if that is what you want me to
do.
-- 
"Long noun chains don't automatically imply security."
--Bruce Schneier