Moved elevation and road distance values to sentinel ones (-9999) instead of nothing

src/FACT_elevation.jl

@@ -34,12 +34,12 @@ function elevation_data_full(ws_host_port::String, selection::Dict)
     
     for (id, shape) in zip(geo_id, shape_obj)
         # setting starting values to nothing
-        min_elevation = nothing
-        max_elevation = nothing
-        mean_elevation = nothing
-        std_elevation = nothing
-        median_elevation = nothing
-        entropy_elevation = nothing
+        min_elevation = -9999 #sentinel value
+        max_elevation = -9999 #sentinel value
+        mean_elevation = -9999 #sentinel value
+        std_elevation = -9999 #sentinel value
+        median_elevation = -9999 #sentinel value
+        entropy_elevation = -9999 #sentinel value
 
 
         # Construct the JSON payload

src/FACT_road.jl

@@ -49,7 +49,7 @@ function travel_time_in_minutes(ws_host_port::String, selection::Dict)
             # Construct the request URL
             url = "$ws_host_port/route/v1/driving/$(start_longitude),$(start_latitude);$(end_longitude),$(end_latitude)?overview=false"
 
-            travel_time = nothing  # Use `nothing` to represent null in Julia
+            travel_time = -9999 #sentinel value
 
             try
                 # Make the request