fixup! TB 31286: Implementation of bridge, proxy, and firewall settings in...

fixup! TB 31286: Implementation of bridge, proxy, and firewall settings in about:preferences#connection

TB 43547: Removing the last bridge sets the source to Invalid instead.

browser/components/torpreferences/content/connectionPane.js

@@ -739,9 +739,16 @@ const gBridgeGrid = {
       }
       strings.splice(index, 1);
 
+      if (strings.length) {
         TorSettings.changeSettings({
           bridges: { source, bridge_strings: strings },
         });
+      } else {
+        // Remove all bridges and disable.
+        TorSettings.changeSettings({
+          bridges: { source: TorBridgeSource.Invalid },
+        });
+      }
     });
   },