–– Pkl Error ––
`Bar` is not a valid supertype.

x | class Baz extends Bar
                      ^^^
at extendTypeAlias#Baz (file:///$snippetsDir/input/errors/extendTypeAlias.pkl)

xxx | text = renderer.renderDocument(value)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
at pkl.base#Module.output.text (pkl:base)
