add missing type annotations

demessaging/NetCDFDecoder.py

@@ -12,6 +12,7 @@ import struct
 from typing import List
 
 import numpy as np
+import numpy.typing as npt
 import xarray as xr
 
 
@@ -35,8 +36,8 @@ def decode(netcdfObject: str) -> xr.Dataset:
     extent = netcdf_json["extent"]
 
     # init latitude and longitude arrays
-    lons = []
-    lats = []
+    lons: npt.ArrayLike = np.array([], dtype=float)
+    lats: npt.ArrayLike = np.array([], dtype=float)
 
     dataset = {}
     for parameter in parameters: