fix: datePicker valueFormat log warning, close #5323

Author: tangjinzhou

components/calendar/generateCalendar.tsx

@@ -127,15 +127,15 @@ function generateCalendar<
             ? (generateConfig.toDate(props.value, props.valueFormat) as DateType)
             : (props.value as DateType);
         }
-        return props.value as DateType;
+        return null;
       });
       const defaultValue = computed(() => {
         if (props.defaultValue) {
           return props.valueFormat
             ? (generateConfig.toDate(props.defaultValue, props.valueFormat) as DateType)
             : (props.defaultValue as DateType);
         }
-        return props.defaultValue as DateType;
+        return null;
       });
 
       // Value

components/date-picker/generatePicker/generateSinglePicker.tsx

@@ -119,15 +119,15 @@ export default function generateSinglePicker<DateType, ExtraProps = {}>(
               ? generateConfig.toDate(props.value as string | DateType, props.valueFormat)
               : props.value;
           }
-          return props.value;
+          return null;
         });
         const defaultValue = computed(() => {
           if (props.defaultValue) {
             return props.valueFormat
               ? generateConfig.toDate(props.defaultValue as string | DateType, props.valueFormat)
               : props.defaultValue;
           }
-          return props.defaultValue;
+          return null;
         });
         const defaultPickerValue = computed(() => {
           if (props.defaultPickerValue) {
@@ -138,7 +138,7 @@ export default function generateSinglePicker<DateType, ExtraProps = {}>(
                 )
               : props.defaultPickerValue;
           }
-          return props.defaultPickerValue;
+          return null;
         });
 
         return () => {