Throwing error when add_constant is not called with float or int

Author: erikvansebille

parcels/fieldset.py

@@ -164,8 +164,8 @@ def add_constant(self, name, value):
         """
         if name in self.constants:
             raise ValueError(f"FieldSet already has a constant with name '{name}'")
-        if isinstance(value, np.timedelta64):
-            value = value / np.timedelta64(1, "s")  # Convert to seconds
+        if not isinstance(value, (float, np.float32, int, np.int32)):
+            raise ValueError(f"FieldSet constants have to be of type float or int, got a {type(value)}")
         self.constants[name] = np.float32(value)
 
     @property

tests/v4/test_diffusion.py

@@ -75,7 +75,7 @@ def test_fieldKh_SpatiallyVaryingDiffusion(mesh_type, kernel):
     Kh_meridional = Field("Kh_meridional", ds["Kh_meridional"], grid=grid, mesh_type=mesh_type, interp_method=XBiLinear)
     UV = VectorField("UV", U, V)
     fieldset = FieldSet([U, V, UV, Kh_zonal, Kh_meridional])
-    fieldset.add_constant("dres", ds["lon"][1] - ds["lon"][0])
+    fieldset.add_constant("dres", float(ds["lon"][1] - ds["lon"][0]))
 
     npart = 100