Propagate error from parsing at rules.

Author: jdm

src/rules_and_declarations.rs

@@ -462,16 +462,14 @@ fn parse_at_rule<'i: 't, 't, P, E>(start_position: SourcePosition, name: Compact
                 _ => unreachable!()
             }
         }
-        Err(_) => {
+        Err(error) => {
             let end_position = input.position();
-            let error = match input.next() {
-                Ok(Token::CurlyBracketBlock) => BasicParseError::UnexpectedToken(Token::CurlyBracketBlock),
-                Ok(Token::Semicolon) => BasicParseError::UnexpectedToken(Token::Semicolon),
-                Err(e) => e,
+            match input.next() {
+                Ok(Token::CurlyBracketBlock) | Ok(Token::Semicolon) | Err(_) => {},
                 _ => unreachable!()
             };
             Err(PreciseParseError {
-                error: ParseError::Basic(error),
+                error: error,
                 span: start_position..end_position,
             })
         }