Update data.py (#1283)

* Update target_array check in data.py

fedot/core/data/data.py

@@ -97,7 +97,7 @@ def from_numpy_time_series(cls,
                         """
         if isinstance(task, str):
             task = Task(TaskTypesEnum(task))
-        if not target_array:
+        if target_array is None:
             target_array = features_array
         return array_to_input_data(features_array, target_array, idx, task, data_type)