[MM-14740] Address potential race condition and cleanup main.js (#968)

A potential race condition between loading registry data in Windows and the electron app becoming ready is fixed with Promise.all() to make sure they are both loaded before finishing initialization that relies on both. Code has been reorganized to support this.

src/common/config/RegistryConfig.js

@@ -9,6 +9,9 @@ import WindowsRegistry from 'winreg';
 const REGISTRY_HIVE_LIST = [WindowsRegistry.HKLM, WindowsRegistry.HKCU];
 const BASE_REGISTRY_KEY_PATH = '\\Software\\Policies\\Mattermost';
 
+/**
+ * Handles loading config data from the Windows registry set manually or by GPO
+ */
 export default class RegistryConfig extends EventEmitter {
   constructor() {
     super();
@@ -17,6 +20,12 @@ export default class RegistryConfig extends EventEmitter {
       teams: [],
     };
   }
+
+  /**
+   * Triggers loading data from Windows registry, supports async/await
+   *
+   * @emits {update} emitted once all data has been loaded from the registry
+   */
   async init() {
     if (process.platform === 'win32') {
       // extract DefaultServerList from the registry
@@ -48,11 +57,14 @@ export default class RegistryConfig extends EventEmitter {
       } catch (error) {
         console.log('[RegistryConfig] Nothing retrieved for \'EnableAutoUpdater\'', error);
       }
-
-      this.initialized = true;
-      this.emit('update', this.data);
     }
+    this.initialized = true;
+    this.emit('update', this.data);
   }
+
+  /**
+   * Extracts a list of servers
+   */
   async getServersListFromRegistry() {
     const defaultTeams = await this.getRegistryEntry(`${BASE_REGISTRY_KEY_PATH}\\DefaultServerList`);
     return defaultTeams.flat(2).reduce((teams, team) => {
@@ -66,18 +78,30 @@ export default class RegistryConfig extends EventEmitter {
     }, []);
   }
 
+  /**
+   * Determines whether server management has been enabled, disabled or isn't configured
+   */
   async getEnableServerManagementFromRegistry() {
     const entries = (await this.getRegistryEntry(BASE_REGISTRY_KEY_PATH, 'EnableServerManagement'));
     const entry = entries.pop();
     return entry ? entry === '0x1' : null;
   }
 
+  /**
+   * Determines whether the auto updated has been enabled, disabled or isn't configured
+   */
   async getEnableAutoUpdatorFromRegistry() {
     const entries = (await this.getRegistryEntry(BASE_REGISTRY_KEY_PATH, 'EnableAutoUpdater'));
     const entry = entries.pop();
     return entry ? entry === '0x1' : null;
   }
 
+  /**
+   * Initiates retrieval of a specific key in the Windows registry
+   *
+   * @param {string} key Path to the registry key to return
+   * @param {string} name Name of specific entry in the registry key to retrieve (optional)
+   */
   async getRegistryEntry(key, name) {
     const results = [];
     for (const hive of REGISTRY_HIVE_LIST) {
@@ -87,6 +111,12 @@ export default class RegistryConfig extends EventEmitter {
     return entryValues.filter((value) => value);
   }
 
+  /**
+   * Handles actual retrieval of entries from a configured WindowsRegistry instance
+   *
+   * @param {WindowsRegistry} regKey A configured instance of the WindowsRegistry class
+   * @param {string} name Name of the specific entry to retrieve (optional)
+   */
   getRegistryEntryValues(regKey, name) {
     return new Promise((resolve) => {
       regKey.values((error, items) => {