If scope was set to "line_breaks" or lower (compare tidyverse_style()),
we can compare the expression before and after styling and return an error if
it is not the same.
If that's not possible, a weaker guarantee that we want to give is that the
resulting code is parsable.
styler:::verify_roundtrip("a+1", "a + 1")
styler:::verify_roundtrip("a+1", "a + 1 # comments are dropped")
if (FALSE) {
styler:::verify_roundtrip("a+1", "b - 3")
}