lex: fix incorrect keyword recognition

src/lex/mod.rs

@@ -245,9 +245,8 @@ impl Lexer {
     fn skip_if_match(&mut self, s: &str) -> bool {
         let mut n: usize = 0;
         for c in s.chars() {
-            if self.cursor.next() == Some(c) {
+            n += 1;
-                n += 1;
+            if self.cursor.next() != Some(c) {
-            } else {
                 self.cursor.seek_back(n);
                 return false;
             }