Checks for valid input and returns warning or errors messages:
assert_atomic_vector(),
assert_character_scalar(),
assert_character_vector(),
assert_data_frame(),
assert_date_vector(),
assert_expr(),
assert_expr_list(),
assert_filter_cond(),
assert_function(),
assert_integer_scalar(),
assert_list_element(),
assert_list_of(),
assert_logical_scalar(),
assert_numeric_vector(),
assert_one_to_one(),
assert_param_does_not_exist(),
assert_s3_class(),
assert_same_type(),
assert_symbol(),
assert_unit(),
assert_vars(),
assert_varval_list()