Can't install Xcode 10.2 from App Store because "There is not enough disk space available to install the product"

Double-check your storage space. Apple never uses the word “free” anymore. They only say “available” now. (Technically not true. They do use the word “free” in one place, but it is a typo. The value is “available”).

The “available” space means the space that the operating system could make “available” if you needed it. But, in practice, that doesn’t always work. Sometimes, the operating system simply fills up your hard drive and then you’re done.