Expecting students to use a code base that is known to be buggy? Suppose an instructor is teaching a course on a particular field in computer science. He uses a language that is popular for said field, but itself is not the topic of the course (though its use is still required).  The instructor provides a code base he wrote that the students may base their course project upon.  However, this code base is very buggy and does not follow many accepted "best practices" in the language's usage.  You are not technically required to use this code base, but to use anything else is most likely impractical given time constraints.  Is it justifiable to expect students to use a buggy code base you prepared, or is it lazy?  Or neither?
The answer to this question is "Sometimes." 

Given that an instructor has roughly X hours/week to devote to this course (given their other responsibilities), sometimes the best way to utilize that time may be to write a code base for students to use in some fraction of those hours (even though it will be buggy and not up to best practices) and devote the rest of those hours to other things. 

Sometimes improving the code base isn't the best way to utilize instructor time - sometimes that time is better used offering more office hours to answer students' questions, or writing better lecture notes, or something else that is of greater benefit to the students' learning than making the code less buggy. 

It's usually up to the instructor to make that determination of what will best serve the pedagogical goals of the course.

(I'm assuming the professor isn't intentionally trying to give students some experience working with a buggy code base. But that's also a possibility.)

As a student, I didn't think about the time and resources my professors devoted to preparing their course materials. As an instructor, I gained a very different perspective. 

For example, the first course I taught as instructor of record was a course that I was only assigned about a week before class started, in a subject outside my area of expertise, and I had very limited time to prep the first few lectures and assignments. I agreed to teach it despite knowing that my teaching would be underprepared (by my own standards) for the first part of the course, because I thought it would be better for my students than the alternative (the course being cancelled because the department couldn't find any other coverage.) As a student, I would never have thought about my professors being put in situations like that.