Previously it would try to parse the semicolon as its own statement and
produce an `nkEmpty` node
Also more than 1 semicolon in an expression list i.e. `(a;; b)` gives an
"expression expected" error in `semiStmtList` when multiple semicolons
are allowed in normal statements, this could be fixed by changing the
`if tok.kind == tokSemicolon` check to a `while` but it does not match
the grammar so not done here.
(cherry picked from commit 918f972369)
72190536cb