result

./automysqlbackup/automysqlbackup: line 835: 6: Bad file descriptor
./automysqlbackup/automysqlbackup: line 836: 7: Bad file descriptor

script.sh

# @info:  Restore stdout and stderr redirections.
# @deps:  (none)
removeIO() {
  exec 1>&6 6>&-      # Restore stdout and close file descriptor #6.
  exec 2>&7 7>&-      # Restore stdout and close file descriptor #7.
}

This issue can be fixed by using the correct syntax:

# @info:        Restore stdout and stderr redirections.
# @deps:        (none)
removeIO() {
  exec 1<&6 6>&-      # Restore stdout and close file descriptor #6.
  exec 2<&7 7>&-      # Restore stdout and close file descriptor #7.
}