only allow for valid urls in slack button (#5312)

server/notification-providers/slack.js

@@ -1,7 +1,7 @@
 const NotificationProvider = require("./notification-provider");
 const axios = require("axios");
 const { setSettings, setting } = require("../util-server");
-const { getMonitorRelativeURL, UP } = require("../../src/util");
+const { getMonitorRelativeURL, UP, log } = require("../../src/util");
 
 class Slack extends NotificationProvider {
     name = "slack";
@@ -50,15 +50,20 @@ class Slack extends NotificationProvider {
 
         const address = this.extractAddress(monitorJSON);
         if (address) {
-            actions.push({
-                "type": "button",
-                "text": {
-                    "type": "plain_text",
-                    "text": "Visit site",
-                },
-                "value": "Site",
-                "url": address,
-            });
+            try {
+                actions.push({
+                    "type": "button",
+                    "text": {
+                        "type": "plain_text",
+                        "text": "Visit site",
+                    },
+                    "value": "Site",
+                    "url": new URL(address),
+                });
+
+            } catch (e) {
+                log.debug("slack", `Failed to parse address ${address} as URL`);
+            }
         }
 
         return actions;