"Format string contains an unescaped latin alphabet character v" using "formatRelative" and "sk" locale

[MartinMikusat]

Here's a CodeSandbox with the issue
https://codesandbox.io/s/date-fns-bug-qf1db?file=/src/index.js

Doesn't happen with all dates, only some. I wasn't able to find any clues to what exactly is causing this.

[fturmel]

Hi, I just stumbled on your issue.

This definitely is a bug. This error message comes from the format method. I tracked it down to a format string in the sk locale that is not escaped properly.

nextWeek Sun/Sat/Wed returns an unescaped string. The štvrtok string contains a v and would throw the error in your example. Should be an easy fix, I'll work on a PR.

date-fns/src/locale/sk/_lib/formatRelative/index.js

Line 44 in ea3f050

return "'budúcu' " + weekday + " 'o' p"

date-fns/src/locale/sk/_lib/formatRelative/index.js

Lines 4 to 12 in ea3f050

	var accusativeWeekdays = [
	'nedeľu',
	'pondelok',
	'utorok',
	'stredu',
	'štvrtok',
	'piatok',
	'sobotu'
	]