Fix subtract on string error

src/index.js

@@ -141,12 +141,14 @@ async function startLoadDataProcess(token, usagePointID) {
     await launchLoadDataProcess(token, usagePointID, startLoadDate, endDate)
   } else {
     log('info', 'launch process with history')
-    for (var i = 1; i < 5; i++) {
+    const startDateToIncrement = moment().subtract(7, 'day')
+    const endDateToIncrement = moment()
+    for (var i = 0; i < 4; i++) {
       await launchLoadDataProcess(
         token,
         usagePointID,
-        startLoadDate.subtract(7 * i, 'day'),
-        endDate.subtract(7 * i, 'day')
+        startDateToIncrement.subtract(7 * i, 'day').format('YYYY-MM-DD'),
+        endDateToIncrement.subtract(7 * i, 'day').format('YYYY-MM-DD')
       )
     }
   }