Handle json decode error in is.gd

.vscode/launch.json

@@ -0,0 +1,15 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "Run CloudBot",
+            "type": "python",
+            "request": "launch",
+            "module": "cloudbot",
+            "justMyCode": true
+        }
+    ]
+}

cloudbot/util/web.py

@@ -222,17 +222,23 @@ def paste(self, data, ext):
 
 class Isgd(Shortener):
     def shorten(self, url, custom=None, key=None):
-        p = {"url": url, "shorturl": custom, "format": "json"}
+        p = {"url": url, "format": "json"}
+        if custom:
+            p['shorturl'] = custom
+
         try:
-            r = requests.get("http://is.gd/create.php", params=p)
+            r = requests.get("https://is.gd/create.php", params=p)
             r.raise_for_status()
         except HTTPError as e:
             r = e.response
             raise ServiceHTTPError(r.reason, r) from e
         except RequestException as e:
             raise ServiceError(e.request, "Connection error occurred") from e
 
-        j = r.json()
+        try:
+            j = r.json()
+        except requests.exceptions.JSONDecodeError as e:
+            raise ServiceError(r.request, str(e))
 
         if "shorturl" in j:
             return j["shorturl"]