@purcell from MELPA said:

"Don't use your own major mode hook like this. Instead, provide a
defcustom called something like "mint-format-on-save", and then add
mint-format-on-save-maybe to before-save-hook. Note that I say
before-save-hook, while you're currently using after-save-hook:
mint-format-file wrongly assumes that every buffer will have an
associated file, which is not true. mint-format-file should instead
either copy the current buffer's contents to a temporary file, or you
can use call-process-region/shell-command-on-region if mint format can
read from STDIN."

Easier than a separate Package-Requires declaration for `seq`.

The former is the standard spelling in Emacs.