Randomization endpoint should not respond with internall server error on data validation

[lwalejko]

This test case suggests that there is unhandled validation case for this endpoint:

unbiased/tests/testthat/test-E2E-study-minimisation-pocock.R

Lines 169 to 226 in 6cd8b92

	test_that("request with patient that is assigned an arm at entry", {
	response <- request(api_url) |>
	req_url_path("study", "minimisation_pocock") |>
	req_method("POST") |>
	req_body_json(
	data = list(
	identifier = "ABC-X",
	name = "Study ABC-X",
	method = "var",
	p = 0.85,
	arms = list(
	"placebo" = 1,
	"active" = 1
	),
	covariates = list(
	sex = list(
	weight = 1,
	levels = c("female", "male")
	),
	weight = list(
	weight = 1,
	levels = c("up to 60kg", "61-80 kg", "81 kg or more")
	)
	)
	)
	) |>
	req_perform()
	response_body <-
	response |>
	resp_body_json()
	response_current_state <-
	tryCatch(
	{
	request(api_url) |>
	req_url_path("study", response_body$study$id, "patient") |>
	req_method("POST") |>
	req_body_json(
	data = list(
	current_state =
	tibble::tibble(
	"sex" = c("female", "male"),
	"weight" = c("61-80 kg", "81 kg or more"),
	"arm" = c("placebo", "control")
	)
	)
	) |>
	req_perform()
	},
	error = function(e) e
	)
	testthat::expect_equal(
	response_current_state$status, 500,
	label = "HTTP status code"
	)
	})

We should always validate input data in a way that will prevent the app from returning Internal Server Errors.