Input check for new_param_grid()

[hfrick]

Does this check ever get executed? Brought up by @EmilHvitfeldt #351 (comment)

dials/R/grids.R

Lines 261 to 265 in 555493b

	if (!is.data.frame(x)) {
	cli::cli_abort(
	"{.arg x} must be a data frame to construct a new grid from."
	)
	}

[topepo]

No, I don't think so. Go ahead and remove it.