fix parsing hole (see #3915)

parser.ml

@@ -1195,7 +1195,8 @@ and expr = parser
 		| [< >] -> serror())
 	| [< '(POpen,p1); e = expr; s >] -> (match s with parser
 		| [< '(PClose,p2); s >] -> expr_next (EParenthesis e, punion p1 p2) s
-		| [< t = parse_type_hint; '(PClose,p2); s >] -> expr_next (EParenthesis (ECheckType(e,t),punion p1 p2), punion p1 p2) s)
+		| [< t = parse_type_hint; '(PClose,p2); s >] -> expr_next (EParenthesis (ECheckType(e,t),punion p1 p2), punion p1 p2) s
+		| [< >] -> serror())
 	| [< '(BkOpen,p1); l = parse_array_decl; '(BkClose,p2); s >] -> expr_next (EArrayDecl l, punion p1 p2) s
 	| [< inl, p1 = inline_function; name = popt dollar_ident; pl = parse_constraint_params; '(POpen,_); al = psep Comma parse_fun_param; '(PClose,_); t = parse_type_opt; s >] ->
 		let make e =