Additional null check

Author: carlosame

ci/io/github/css4j/ci/BaseSiteErrorReporter.java

@@ -198,7 +198,7 @@ public void ruleSelectorError(StyleRule stylerule, SelectorList selist, Selector
 			String selectorText, int sheetIndex, int ruleIndex, AbstractCSSStyleSheet parent) {
 		writeSerializationError("Selector reparse error in rule: " + ruleIndex + " in sheet " + parent.getHref() + ":");
 		writeSerializationError("List 1 (CSSOM): " + stylerule.getSelectorText());
-		writeSerializationError("List 2 (CSSOM): " + selectorText);
+		writeSerializationError("List 2 (CSSOM): " + (selectorText == null ? "null" : selectorText));
 		writeSerializationError("List 1  (NSAC): " + (selist == null ? "null" : selist.toString()));
 		writeSerializationError("List 2  (NSAC): " + (otherSelist == null ? "null" : otherSelist.toString()));
 	}

ci/io/github/css4j/ci/SampleSitesIT.java

@@ -872,14 +872,17 @@ private boolean checkSelectors(StyleRule stylerule, int sheetIndex, int ruleInde
 		SelectorList selist = stylerule.getSelectorList();
 		String cssText = stylerule.getCssText();
 		StyleRule orule = (StyleRule) parseRule(cssText);
+
 		SelectorList oselist = null;
+		String oseltext = null;
 		boolean result = false;
 		if (orule != null) {
 			oselist = orule.getSelectorList();
+			oseltext = orule.getSelectorText();
 			result = ParseHelper.equalSelectorList(selist, oselist);
 		}
 		if (!result) {
-			reporter.ruleSelectorError(stylerule, selist, oselist, orule.getSelectorText(),
+			reporter.ruleSelectorError(stylerule, selist, oselist, oseltext,
 					sheetIndex, ruleIndex, sheet);
 		}
 		return result;