convert2rhel analyze command fails with error "GRUB_VALIDITY::INVALID_GRUB_FILE - Grub boot entry file is invalid"

Issue

• convert2rhel analyze command fails with below error :

  ========== Error (Must fix before conversion) ==========
  (ERROR) GRUB_VALIDITY::INVALID_GRUB_FILE - Grub boot entry file is invalid
       Description: The grub file seems to be invalid leaving the system in a non-clean state and must be fixed before continuing     the conversion to ensure a smooth process.
       Diagnosis: N/A
       Remediations: Check the grub file inside `/etc/default` directory and remove any misconfigurations, then re-run the conversion.