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
@@ -166,6 +167,7 @@ def get_streets(
     # Boundary defined by polygon (perimeter)
     if perimeter is not None:
         # Fetch streets data, project & convert to GDF
+        try:
             streets = ox.graph_from_polygon(
                 unary_union(perimeter.geometry).buffer(buffer)
                 if buffer > 0
@@ -174,9 +176,12 @@ def get_streets(
             )
             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
+        try:
             streets = ox.graph_from_point(
                 point,
                 dist=radius + dilate + buffer,
@@ -192,6 +197,8 @@ def get_streets(
             # 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(