catch empty response instead of failing

If a street is present in the layers with a custom filter that does not
exist in the specified area, osmnx throws an exception and the whole
plotting fails. I suggest catching the exception and just returning an
empty `MultiLineString`. Maybe a warning could also be added, to inform
that the requested street is not present in the result.

prettymaps/fetch.py

@@ -2,6 +2,7 @@ from functools import reduce
 
 import osmnx as ox
 from osmnx import utils_geo
+from osmnx._errors import EmptyOverpassResponse
 import numpy as np
 from shapely.geometry import Point, Polygon, MultiPolygon, MultiLineString
 from shapely.ops import unary_union
@@ -166,32 +167,38 @@ def get_streets(
     # Boundary defined by polygon (perimeter)
     if perimeter is not None:
         # Fetch streets data, project & convert to GDF
-        streets = ox.graph_from_polygon(
-            unary_union(perimeter.geometry).buffer(buffer)
-            if buffer > 0
-            else unary_union(perimeter.geometry),
-            custom_filter=custom_filter,
-        )
-        streets = ox.project_graph(streets)
-        streets = ox.graph_to_gdfs(streets, nodes=False)
+        try:
+            streets = ox.graph_from_polygon(
+                unary_union(perimeter.geometry).buffer(buffer)
+                if buffer > 0
+                else unary_union(perimeter.geometry),
+                custom_filter=custom_filter,
+            )
+            streets = ox.project_graph(streets)
+            streets = ox.graph_to_gdfs(streets, nodes=False)
+        except EmptyOverpassResponse:
+            return MultiLineString()
     # Boundary defined by polygon (perimeter)
     elif (point is not None) and (radius is not None):
         # Fetch streets data, save CRS & project
-        streets = ox.graph_from_point(
-            point,
-            dist=radius + dilate + buffer,
-            retain_all=retain_all,
-            custom_filter=custom_filter,
-        )
-        crs = ox.graph_to_gdfs(streets, nodes=False).crs
-        streets = ox.project_graph(streets)
-        # Compute perimeter from point & CRS
-        perimeter = get_boundary(point, radius, crs, circle=circle, dilate=dilate)
-        # Convert to GDF
-        streets = ox.graph_to_gdfs(streets, nodes=False)
-        # Intersect with perimeter & filter empty elements
-        streets.geometry = streets.geometry.intersection(perimeter)
-        streets = streets[~streets.geometry.is_empty]
+        try:
+            streets = ox.graph_from_point(
+                point,
+                dist=radius + dilate + buffer,
+                retain_all=retain_all,
+                custom_filter=custom_filter,
+            )
+            crs = ox.graph_to_gdfs(streets, nodes=False).crs
+            streets = ox.project_graph(streets)
+            # Compute perimeter from point & CRS
+            perimeter = get_boundary(point, radius, crs, circle=circle, dilate=dilate)
+            # Convert to GDF
+            streets = ox.graph_to_gdfs(streets, nodes=False)
+            # Intersect with perimeter & filter empty elements
+            streets.geometry = streets.geometry.intersection(perimeter)
+            streets = streets[~streets.geometry.is_empty]
+        except EmptyOverpassResponse:
+            return MultiLineString()
 
     if type(width) == dict:
         streets = unary_union(