r.valley.bottom compatibility with r.neighbors for grass8

src/raster/r.valley.bottom/r.valley.bottom.py

@@ -117,6 +117,8 @@
 from grass.pygrass.gis.region import Region
 from grass.pygrass.modules.shortcuts import general as g
 from grass.pygrass.modules.shortcuts import raster as r
+from grass.exceptions import ParameterError
+
 
 if "GISBASE" not in os.environ:
     print("You must be in GRASS GIS to run this program.")
@@ -492,7 +494,12 @@ def smooth_dem(DEM):
 
     smoothed = rand_id("smoothed{}".format(L + 1))
     TMP_RAST[L].append(smoothed)
-    r.neighbors(input=DEM, output=smoothed, size=11, gauss=3)
+
+    try:
+        r.neighbors(input=DEM, output=smoothed, size=11, gauss=3)
+    except ParameterError:
+        r.neighbors(input=DEM, output=smoothed, size=11, weighting_function="gaussian",
+                    weighting_factor=3)
 
     return smoothed