More fixing for bug #71540

ext/xsl/tests/bug71540.phpt

@@ -55,6 +55,8 @@ Warning: XSLTProcessor::transformToXml(): Stack usage errror in %sbug71540.php o
 
 Warning: XSLTProcessor::transformToXml(): Stack usage errror in %sbug71540.php on line %d
 
+Warning: XSLTProcessor::transformToXml(): Handler name must be a string in %sbug71540.php on line %d
+
 Warning: XSLTProcessor::transformToXml(): xmlXPathCompiledEval: 2 objects left on the stack. in %sbug71540.php on line %d
 
 Warning: XSLTProcessor::transformToXml(): runtime error: file %s line 13 element value-of in %sbug71540.php on line %d

ext/xsl/xsltprocessor.c

@@ -304,7 +304,7 @@ static void xsl_ext_function_php(xmlXPathParserContextPtr ctxt, int nargs, int t
 
 
 	obj = valuePop(ctxt);
-	if (obj->stringval == NULL) {
+	if (obj == NULL || obj->stringval == NULL) {
 		php_error_docref(NULL, E_WARNING, "Handler name must be a string");
 		xmlXPathFreeObject(obj);
 		valuePush(ctxt, xmlXPathNewString((const xmlChar *) ""));