parser: check error early

src/parser.rs

@@ -25,9 +25,9 @@ impl<'a> Parser<'a> {
             ),
             TokenKind::StringLiteral => self.node_result(ident.raw, NodeVal::String(val.raw)),
             _ => self.lexer.syntax_error(String::from("Expected a value")),
-        };
+        }?;
         self.require_kind(TokenKind::Semi)?;
-        node
+        Ok(node)
     }
 
     fn require_kind(&mut self, kind: TokenKind) -> Result<Token, SyntaxError> {