Addede NULL check some of mac neighbor table check.

Author: Juha Heiskanen

source/Service_Libs/mac_neighbor_table/mac_neighbor_table.c

@@ -79,6 +79,9 @@ static void neighbor_table_class_remove_entry(mac_neighbor_table_t *table_class,
 
 void mac_neighbor_table_neighbor_list_clean(mac_neighbor_table_t *table_class)
 {
+    if (!table_class) {
+        return;
+    }
     ns_list_foreach_safe(mac_neighbor_table_entry_t, cur, &table_class->neighbour_list) {
         neighbor_table_class_remove_entry(table_class, cur);
     }
@@ -87,6 +90,9 @@ void mac_neighbor_table_neighbor_list_clean(mac_neighbor_table_t *table_class)
 
 void mac_neighbor_table_neighbor_timeout_update(mac_neighbor_table_t *table_class, uint32_t time_update)
 {
+    if (!table_class) {
+        return;
+    }
     bool nud_is_enabled = false;
     if (table_class->nud_threshold && table_class->user_nud_notify_cb) {
         nud_is_enabled = true;
@@ -124,6 +130,9 @@ void mac_neighbor_table_neighbor_timeout_update(mac_neighbor_table_t *table_clas
 
 mac_neighbor_table_entry_t *mac_neighbor_table_entry_allocate(mac_neighbor_table_t *table_class, const uint8_t *mac64)
 {
+    if (!table_class) {
+        return NULL;
+    }
     mac_neighbor_table_entry_t *entry = ns_list_get_first(&table_class->free_list);
     if (!entry) {
         return NULL;
@@ -194,6 +203,9 @@ void mac_neighbor_table_trusted_neighbor(mac_neighbor_table_t *table_class, mac_
 
 mac_neighbor_table_entry_t *mac_neighbor_table_address_discover(mac_neighbor_table_t *table_class, const uint8_t *address, uint8_t address_type)
 {
+    if (!table_class) {
+        return NULL;
+    }
     uint16_t short_address;
     if (address_type == 2) {
         short_address = common_read_16_bit(address);