IDEMPIERE-2552:sometime has NPE in CLogErrorBuffer

org.adempiere.base/src/org/compiere/util/CLogErrorBuffer.java

@@ -188,6 +188,8 @@ public class CLogErrorBuffer extends Handler
 					loggerName = "";
 				//String className = record.getSourceClassName();		//	physical class
 				String methodName = record.getSourceMethodName();	//
+				if (methodName == null)
+					methodName = "";
 				if (DB.isConnected(false)
 					&& !methodName.equals("saveError")
 					&& !methodName.equals("get_Value")