New developers will create bugs regardless of language. It is a gift, without which they would never learn.

To put my devil's advocate hat on for a minute - new developers will create bugs, but language choice can have a huge effect on what kind of bugs.

For example a newbie developer using a language that naturally supports iteration over containers like Perl's foreach() or Ruby's each() won't hit a whole bunch of off-by-one errors that languages like C curse people with.

I remember very well an introductory AI programming course that I helped teach a few years back. At the same time as the students were building a GUI driven 3D block world in Pop-11 they were bashing their heads against the wall with segfaults with simple "add up a list of numbers" programs in their C based introductory programming course. No experience before or since has been a better demonstration to me that language choice really matters.

I just happen to think that trailing if and unless() are not a major cause of problems for novice developers. Certainly not enough of a problem to remove the gain in clarity that they give to experienced developers.