fix get_node_statistics

Author: yungwine

mytoncore/mytoncore.py

@@ -3047,18 +3047,19 @@ def get_node_statistics(self):
 		:return: stats for collated/validated blocks since round beggining and stats for ls queries for the last minute
 		"""
 		stats = self.local.db.get('statistics', {}).get('node')
-		result = {
-			'collated': {
-				'ok': 0,
-				'error': 0,
-			},
-			'validated': {
-				'ok': 0,
-				'error': 0,
-			}
-		}
+		result = {}
 		if stats is not None and len(stats) == 3 and stats[0] is not None:
 			for k in ['master', 'shard']:
+				result = {
+					'collated': {
+						'ok': 0,
+						'error': 0,
+					},
+					'validated': {
+						'ok': 0,
+						'error': 0,
+					}
+				}
 				collated_ok = stats[2]['collated_blocks'][k]['ok'] - stats[0]['collated_blocks'][k]['ok']
 				collated_error = stats[2]['collated_blocks'][k]['error'] - stats[0]['collated_blocks'][k]['error']
 				validated_ok = stats[2]['validated_blocks'][k]['ok'] - stats[0]['validated_blocks'][k]['ok']
@@ -3075,7 +3076,7 @@ def get_node_statistics(self):
 				result['collated']['error'] += collated_error
 				result['validated']['ok'] += validated_ok
 				result['validated']['error'] += validated_error
-		if stats is not None and len(stats) >= 2:
+		if stats is not None and len(stats) >= 2 and stats[0] is not None:
 			result['ls_queries'] = {
 				'ok': stats[-1]['ls_queries']['ok'] - stats[-2]['ls_queries']['ok'],
 				'error': stats[-1]['ls_queries']['error'] - stats[-2]['ls_queries']['error'],