resolved key issue

package-lock.json

@@ -10036,7 +10036,7 @@
     },
     "prettier": {
       "version": "2.0.5",
-      "resolved": "https://npm.mlabs.pl:443/prettier/-/prettier-2.0.5.tgz",
+      "resolved": "https://registry.npmjs.org/prettier/-/prettier-2.0.5.tgz",
       "integrity": "sha512-7PtVymN48hGcO4fGjybyBSIWDsLU4H4XlvOHfq91pz9kkGlonzwTfYkaIEwiRg/dAJF9YlbsduBAgtYLi+8cFg==",
       "dev": true
     },

src/components/SchedulerRow.tsx

@@ -1,4 +1,4 @@
-import React, { MouseEvent, useState } from 'react';
+import React, { Fragment, MouseEvent, useState } from 'react';
 import { GroupType, SchedulerEvent } from '../types';
 import styled from 'styled-components/macro';
 import Popover from '@material-ui/core/Popover';
@@ -104,7 +104,7 @@ export const SchedulerRow = ({ groups, indexRow, rowTop, cellWidth, cellHeight }
           {groups.map(
             (group, index) =>
               group.day === eventIndex && (
-                <>
+                <Fragment key={index}>
                   <StyledSchedulerEvent
                     groupType={group.type}
                     cellWidth={cellWidth}
@@ -148,7 +148,7 @@ export const SchedulerRow = ({ groups, indexRow, rowTop, cellWidth, cellHeight }
                       <p>{groups[index].room}</p>
                     </StyledTypography>
                   </Popover>
-                </>
+                </Fragment>
               ),
           )}
         </SchedulerEventsWrapper>

src/contexts/CoursesProvider.tsx

@@ -140,8 +140,10 @@ export const CoursesProvider = ({ children }: CoursesProviderProps) => {
   };
 
   useEffect(() => {
-    fetchCourses();
-    getNewestTimetable();
+    setTimeout(() => {
+      fetchCourses();
+      getNewestTimetable();
+    }, 200);
   }, []);
 
   return (