Why does missing GRUB2 modules cause system to end up in `grub >` prompt on reboot?

Issue

• RHEL 8 system post LEAPP IPU from RHEL 7 ends up in grub prompt grub> every reboot.
  

• RHEL 8 system fails with grub prompt grub> after grub2 installation every reboot. If grub.cfg file is attempted to be loaded then it fails with following error:

  error: file '/grub2/i386-pc/increment.mod' not found
  error: can't find command 'blscfg'.
  

• RHEL 7+ system fails with grub prompt grub> after grub2 installation every reboot with following error:

  error: ../../grub-core/script/function.c:119:can't find command '['.
  error: ../../grub-core/script/function.c:119:can't find command 'load_env'.
  error: ../../grub-core/script/function.c:119:can't find command '['.
  error: ../../grub-core/script/function.c:119:can't find command 'save_env'.
  error: ../../grub-core/script/function.c:119:can't find command '['.
  error: ../../grub-core/script/function.c:119:can't find command '['.
  error: ../../grub-core/script/function.c:119:can't find command 'save_env'.
  error: ../../grub-core/script/function.c:119:can't find command 'save_env'.
  error: ../../grub-core/script/function.c:119:can't find command '['.
  error: ../../grub-core/script/function.c:119:can't find command '['.
  error: ../../grub-core/script/function.c:119:can't find command 'source'.
  error: ../../grub-core/script/function.c:119:can't find command '['.
  

  Or

  error: ../../grub-core/script/fshelp.c:258:file 'grub2/i386-pc/test.mod' not found.
  error: ../../grub-core/script/fshelp.c:258:file 'grub2/i386-pc/test.mod' not found.
  error: ../../grub-core/script/fshelp.c:258:file 'grub2/i386-pc/test.mod' not found.
  error: ../../grub-core/script/fshelp.c:258:file 'grub2/i386-pc/test.mod' not found.
  .
  .
  . 
  error: ../../grub-core/script/fshelp.c:258:file 'grub2/i386-pc/test.mod' not found.
  

• RHEL 7+ system shows following error if grub.cfg file is attempted to load from grub>

  error: ../../grub-core/script/fshelp.c:258:file 'grub2/i386-pc/laodenv.mod' not found.
  error: ../../grub-core/script/fshelp.c:258:file 'grub2/i386-pc/laodenv.mod' not found.
  error: ../../grub-core/script/fshelp.c:258:file 'grub2/i386-pc/laodenv.mod' not found.
  error: ../../grub-core/script/fshelp.c:258:file 'grub2/i386-pc/laodenv.mod' not found.