exec cue eval input.textproto schema-required.cue
cmp stdout want-stdout-required

! exec cue eval input.textproto schema-optional.cue
cmp stderr want-stderr-optional

-- input.textproto --
f: 234
-- schema-required.cue --
f!: int64
-- want-stdout-required --
f: 234
-- schema-optional.cue --
f?: string
-- want-stderr-optional --
textproto: invalid string or bytes: invalid quote character 2:
    ./input.textproto:1:1
