tests: make error handling the same as the main function (#15825)

vlib/rand/random_numbers_test.v

@@ -354,7 +354,7 @@ fn test_shuffle() {
 	}
 }
 
-fn test_shuffle_partial() ? {
+fn test_shuffle_partial() {
 	mut a := [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
 	mut b := a.clone()
 
@@ -382,7 +382,7 @@ fn test_shuffle_clone() {
 	}
 }
 
-fn test_choose() ? {
+fn test_choose() {
 	lengths := [1, 3, 4, 5, 6, 7]
 	a := ['one', 'two', 'three', 'four', 'five', 'six', 'seven']
 	for length in lengths {