fix bug

mallinkService/src/main/java/com/iformall/service/helper/WxRentContractHelper.java

@@ -69,6 +69,9 @@ public class WxRentContractHelper {
 					return null;
 				}
 			}else {
+				if (null == fee) {
+					return null;
+				}
 				String rentArea = wxRentContract.getRentArea();
 				if (rentArea == null || rentArea.equalsIgnoreCase("NaN")) {
 	            	rentArea = "0";