message: fix: fix typo, which will case null pointer.
diff: @@ -211,7 +211,7 @@ export default class PatternManager extends Definable {
  super.markDomUsed(patternDomMap.get(displayable.style.fill));
  }
  if (isPattern(displayable.style.stroke)) {
  - super.markDomUsed(patternDomMap.get(displayable.style.fill));
  + super.markDomUsed(patternDomMap.get(displayable.style.stroke));
  }
  }
  }
  