Check data inputs to epidist_prepare

[athowes]

epidist_prepare should check data inputs and give appropriate errors.

test_that("epidist_prepare.default gives an error when passed a list", { # nolint: line_length_linter.
  expect_error(epidist_prepare(list(), model = "latent_individual"))
})

That said, it may be not worth doing this as epidist_prepare will be superceeded by as and is functionality in #73. Though the solution to that issue should also do something similar.

Resources

• Use checkmate for argument checking #45