(de)Register consumer nodes at config node

In order for error messages to be catchable

src/matrix-create-room.js

@@ -11,6 +11,7 @@ module.exports = function(RED) {
             node.error('Server must be configured on the node.', {});
             return;
         }
+        node.server.register(node);
 
         this.encodeUri = function(pathTemplate, variables) {
             for (const key in variables) {
@@ -64,6 +65,10 @@ module.exports = function(RED) {
                     node.send([null, msg]);
                 });
         });
+
+        node.on("close", function() {
+            node.server.deregister(node);
+        });
     }
     RED.nodes.registerType("matrix-create-room", MatrixCreateRoom);
 }