Fix assert() usage.

py/objlist.c

@@ -139,7 +139,9 @@ static mp_obj_t list_binary_op(int op, mp_obj_t lhs, mp_obj_t rhs) {
 #if MICROPY_ENABLE_SLICE
             if (MP_OBJ_IS_TYPE(rhs, &slice_type)) {
                 machine_uint_t start, stop;
-                assert(m_seq_get_fast_slice_indexes(o->len, rhs, &start, &stop));
+                if (!m_seq_get_fast_slice_indexes(o->len, rhs, &start, &stop)) {
+                    assert(0);
+                }
                 mp_obj_list_t *res = list_new(stop - start);
                 m_seq_copy(res->items, o->items + start, res->len, mp_obj_t);
                 return res;

py/objstr.c

@@ -116,7 +116,9 @@ mp_obj_t str_binary_op(int op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
 #if MICROPY_ENABLE_SLICE
             } else if (MP_OBJ_IS_TYPE(rhs_in, &slice_type)) {
                 machine_uint_t start, stop;
-                assert(m_seq_get_fast_slice_indexes(lhs_len, rhs_in, &start, &stop));
+                if (!m_seq_get_fast_slice_indexes(lhs_len, rhs_in, &start, &stop)) {
+                    assert(0);
+                }
                 return mp_obj_new_str(lhs_data + start, stop - start, false);
 #endif
             } else {

py/objtuple.c

@@ -91,7 +91,9 @@ static mp_obj_t tuple_binary_op(int op, mp_obj_t lhs, mp_obj_t rhs) {
 #if MICROPY_ENABLE_SLICE
             if (MP_OBJ_IS_TYPE(rhs, &slice_type)) {
                 machine_uint_t start, stop;
-                assert(m_seq_get_fast_slice_indexes(o->len, rhs, &start, &stop));
+                if (!m_seq_get_fast_slice_indexes(o->len, rhs, &start, &stop)) {
+                    assert(0);
+                }
                 mp_obj_tuple_t *res = mp_obj_new_tuple(stop - start, NULL);
                 m_seq_copy(res->items, o->items + start, res->len, mp_obj_t);
                 return res;