Apply strictNullChecks to src/settings/* (#10252

* Apply strictNullChecks to src/settings/*

* Fix inherited types

src/accessibility/KeyboardShortcuts.ts

@@ -154,7 +154,7 @@ export enum KeyBindingAction {
     ToggleHiddenEventVisibility = "KeyBinding.toggleHiddenEventVisibility",
 }
 
-type KeyboardShortcutSetting = IBaseSetting<KeyCombo>;
+type KeyboardShortcutSetting = Omit<IBaseSetting<KeyCombo>, "supportedLevels">;
 
 // TODO: We should figure out what to do with the keyboard shortcuts that are not handled by KeybindingManager
 export type IKeyboardShortcuts = Partial<Record<KeyBindingAction, KeyboardShortcutSetting>>;

src/settings/Settings.tsx

@@ -126,7 +126,7 @@ export interface IBaseSetting<T extends SettingValueType = SettingValueType> {
 
     // The supported levels are required. Preferably, use the preset arrays
     // at the top of this file to define this rather than a custom array.
-    supportedLevels?: SettingLevel[];
+    supportedLevels: SettingLevel[];
 
     // Required. Can be any data type. The value specified here should match
     // the data being stored (ie: if a boolean is used, the setting should

src/settings/SettingsStore.ts

@@ -45,13 +45,13 @@ const defaultWatchManager = new WatchManager();
 const defaultSettings: Record<string, any> = {};
 const invertedDefaultSettings: Record<string, boolean> = {};
 const featureNames: string[] = [];
-for (const key of Object.keys(SETTINGS)) {
-    defaultSettings[key] = SETTINGS[key].default;
-    if (SETTINGS[key].isFeature) featureNames.push(key);
-    if (SETTINGS[key].invertedSettingName) {
-        // Invert now so that the rest of the system will invert it back
-        // to what was intended.
-        invertedDefaultSettings[SETTINGS[key].invertedSettingName] = !SETTINGS[key].default;
+for (const key in SETTINGS) {
+    const setting = SETTINGS[key];
+    defaultSettings[key] = setting.default;
+    if (setting.isFeature) featureNames.push(key);
+    if (setting.invertedSettingName) {
+        // Invert now so that the rest of the system will invert it back to what was intended.
+        invertedDefaultSettings[setting.invertedSettingName] = !setting.default;
     }
 }
 
@@ -250,7 +250,7 @@ export default class SettingsStore {
             if (roomId === null) {
                 // Unregister all existing watchers and register the new one
                 rooms.forEach((roomId) => {
-                    SettingsStore.unwatchSetting(this.monitors.get(settingName)!.get(roomId));
+                    SettingsStore.unwatchSetting(this.monitors.get(settingName)!.get(roomId)!);
                 });
                 this.monitors.get(settingName)!.clear();
                 registerWatcher();

src/settings/controllers/SlidingSyncController.ts

@@ -29,7 +29,7 @@ export default class SlidingSyncController extends SettingController {
     }
 
     public async onChange(): Promise<void> {
-        PlatformPeg.get().reload();
+        PlatformPeg.get()?.reload();
     }
 
     public get settingDisabled(): boolean {

src/settings/watchers/ThemeWatcher.ts

@@ -53,20 +53,16 @@ export default class ThemeWatcher {
     public start(): void {
         this.themeWatchRef = SettingsStore.watchSetting("theme", null, this.onChange);
         this.systemThemeWatchRef = SettingsStore.watchSetting("use_system_theme", null, this.onChange);
-        if (this.preferDark.addEventListener) {
-            this.preferDark.addEventListener("change", this.onChange);
-            this.preferLight.addEventListener("change", this.onChange);
-            this.preferHighContrast.addEventListener("change", this.onChange);
-        }
+        this.preferDark.addEventListener("change", this.onChange);
+        this.preferLight.addEventListener("change", this.onChange);
+        this.preferHighContrast.addEventListener("change", this.onChange);
         this.dispatcherRef = dis.register(this.onAction);
     }
 
     public stop(): void {
-        if (this.preferDark.addEventListener) {
-            this.preferDark.removeEventListener("change", this.onChange);
-            this.preferLight.removeEventListener("change", this.onChange);
-            this.preferHighContrast.removeEventListener("change", this.onChange);
-        }
+        this.preferDark.removeEventListener("change", this.onChange);
+        this.preferLight.removeEventListener("change", this.onChange);
+        this.preferHighContrast.removeEventListener("change", this.onChange);
         if (this.systemThemeWatchRef) SettingsStore.unwatchSetting(this.systemThemeWatchRef);
         if (this.themeWatchRef) SettingsStore.unwatchSetting(this.themeWatchRef);
         if (this.dispatcherRef) dis.unregister(this.dispatcherRef);
@@ -144,14 +140,14 @@ export default class ThemeWatcher {
         return SettingsStore.getValue("theme");
     }
 
-    private themeBasedOnSystem(): string {
-        let newTheme: string;
+    private themeBasedOnSystem(): string | undefined {
+        let newTheme: string | undefined;
         if (this.preferDark.matches) {
             newTheme = "dark";
         } else if (this.preferLight.matches) {
             newTheme = "light";
         }
-        if (this.preferHighContrast.matches) {
+        if (newTheme && this.preferHighContrast.matches) {
             const hcTheme = findHighContrastTheme(newTheme);
             if (hcTheme) {
                 newTheme = hcTheme;