[MM-53295] Fix crash in diagnostics when server is unreachable (#2771)

* [MM-53295] Fix crash in diagnostics when server is unreachable

* Fix URL parsing, lint fixes

src/main/diagnostics/steps/internal/utils.ts

@@ -70,11 +70,13 @@ export async function isOnline(logger: ElectronLog = log, url = IS_ONLINE_ENDPOI
 
             // The whole response has been received. Print out the result.
             resp.on('end', () => {
-                logger.debug('resp.on.end', {data});
-                const respBody = JSON.parse(data);
-                if (respBody.status === 'OK') {
-                    resolve(true);
-                    return;
+                logger.debug('resp.on.end', {data, url});
+                if (data.length) {
+                    const respBody = JSON.parse(data);
+                    if (respBody.status === 'OK') {
+                        resolve(true);
+                        return;
+                    }
                 }
                 resolve(false);
             });

src/main/diagnostics/steps/step3.serverConnectivity.ts

@@ -5,6 +5,7 @@ import {ElectronLog} from 'electron-log';
 import {DiagnosticStepResponse} from 'types/diagnostics';
 
 import ServerManager from 'common/servers/serverManager';
+import {parseURL} from 'common/utils/url';
 
 import DiagnosticsStep from '../DiagnosticStep';
 
@@ -24,7 +25,7 @@ const run = async (logger: ElectronLog): Promise<DiagnosticStepResponse> => {
                 throw new Error(`Invalid server configuration. Server Url: ${server.url}, server name: ${server.name}`);
             }
 
-            const serverOnline = await isOnline(logger, `${server.url}/api/v4/system/ping`);
+            const serverOnline = await isOnline(logger, parseURL(`${server.url}/api/v4/system/ping`)?.toString());
 
             if (!serverOnline) {
                 throw new Error(`Server appears to be offline. Server url: ${server.url}`);

src/main/server/serverInfo.ts

@@ -4,6 +4,7 @@
 import {ClientConfig, RemoteInfo} from 'types/server';
 
 import {MattermostServer} from 'common/servers/MattermostServer';
+import {parseURL} from 'common/utils/url';
 
 import {getServerAPI} from './serverAPI';
 
@@ -18,8 +19,8 @@ export class ServerInfo {
 
     fetchConfigData = async () => {
         await this.getRemoteInfo<ClientConfig>(
-            new URL(`${this.server.url.toString()}/api/v4/config/client?format=old`),
             this.onGetConfig,
+            parseURL(`${this.server.url}/api/v4/config/client?format=old`),
         );
 
         return this.remoteInfo;
@@ -28,17 +29,20 @@ export class ServerInfo {
     fetchRemoteInfo = async () => {
         await this.fetchConfigData();
         await this.getRemoteInfo<Array<{id: string; version: string}>>(
-            new URL(`${this.server.url.toString()}/api/v4/plugins/webapp`),
             this.onGetPlugins,
+            parseURL(`${this.server.url}/api/v4/plugins/webapp`),
         );
 
         return this.remoteInfo;
     }
 
     private getRemoteInfo = <T>(
-        url: URL,
         callback: (data: T) => void,
+        url?: URL,
     ) => {
+        if (!url) {
+            return Promise.reject(new Error('Malformed URL'));
+        }
         return new Promise<void>((resolve, reject) => {
             getServerAPI<T>(
                 url,