An invalid @charset declaration at the beginning of a style sheet may trigger "weird" error messages.

For instance:
@charset="utf-8";
body { margin: 1em; }

... will return two errors:
- Parse Error @charsetnull;
- The @charset rule may only occur at the start of the style sheet. Please check that there are no spaces before it. @charset="utf-8";

The first error is good but the "null" should be removed.
The second error is probably a collateral damage. It is a bit misleading, but well, no big deal if it cannot be avoided.

Not sure what component is in cause here.