Check that user exists before adding

Author: cunla

.github/workflows/add_member.yml

@@ -36,6 +36,8 @@ jobs:
           python -c "print('USERNAME='+'${{ github.event.issue.title }}'.split(' - ')[1])" >> $GITHUB_ENV
 
       - name: Check whether username exists
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
           gh api /users/${{ env.USERNAME }} > /dev/null
           if [ $? -ne 0 ]; then