language interpreters are "infinite bug sponges". You squeeze them and bugs pour out. You can squeeze and squeeze for years and you will get an unending stream of bugs. Don't believe me? Look at any "mature" interpreted language, go visit its bug database. This is bad because kernels are supposed to be sanctuaries of quality code, not infestations of bugs.
I think you are overgeneralizing. First off, Lua has a VERY small codebase. Second off, it matters about the project, not the type of project.