Enable @typescript-eslint/explicit-function-return-type in /src (#9788)

* Enable `@typescript-eslint/explicit-member-accessibility` on /src

* Prettier

* Enable `@typescript-eslint/explicit-function-return-type` in /src

* Fix types

* tsc strict fixes

* Delint

* Fix test

* Fix bad merge

src/async-components/views/dialogs/eventindex/ManageEventIndexDialog.tsx

@@ -56,7 +56,7 @@ export default class ManageEventIndexDialog extends React.Component<IProps, ISta
         };
     }
 
-    public updateCurrentRoom = async (room) => {
+    public updateCurrentRoom = async (room): Promise<void> => {
         const eventIndex = EventIndexPeg.get();
         let stats;
 
@@ -131,17 +131,17 @@ export default class ManageEventIndexDialog extends React.Component<IProps, ISta
         });
     }
 
-    private onDisable = async () => {
+    private onDisable = async (): Promise<void> => {
         const DisableEventIndexDialog = (await import("./DisableEventIndexDialog")).default;
         Modal.createDialog(DisableEventIndexDialog, null, null, /* priority = */ false, /* static = */ true);
     };
 
-    private onCrawlerSleepTimeChange = (e) => {
+    private onCrawlerSleepTimeChange = (e): void => {
         this.setState({ crawlerSleepTime: e.target.value });
         SettingsStore.setValue("crawlerSleepTime", null, SettingLevel.DEVICE, e.target.value);
     };
 
-    public render() {
+    public render(): JSX.Element {
         const brand = SdkConfig.get().brand;
 
         let crawlerState;

src/async-components/views/dialogs/security/CreateKeyBackupDialog.tsx

@@ -125,7 +125,7 @@ export default class CreateKeyBackupDialog extends React.PureComponent<IProps, I
         let info;
         try {
             if (secureSecretStorage) {
-                await accessSecretStorage(async () => {
+                await accessSecretStorage(async (): Promise<void> => {
                     info = await MatrixClientPeg.get().prepareKeyBackupVersion(null /* random key */, {
                         secureSecretStorage: true,
                     });

src/async-components/views/dialogs/security/CreateSecretStorageDialog.tsx

@@ -350,7 +350,7 @@ export default class CreateSecretStorageDialog extends React.PureComponent<IProp
                     createSecretStorageKey: async () => this.recoveryKey,
                     keyBackupInfo: this.state.backupInfo,
                     setupNewKeyBackup: !this.state.backupInfo,
-                    getKeyBackupPassphrase: async () => {
+                    getKeyBackupPassphrase: async (): Promise<Uint8Array> => {
                         // We may already have the backup key if we earlier went
                         // through the restore backup path, so pass it along
                         // rather than prompting again.
@@ -383,7 +383,9 @@ export default class CreateSecretStorageDialog extends React.PureComponent<IProp
     private restoreBackup = async (): Promise<void> => {
         // It's possible we'll need the backup key later on for bootstrapping,
         // so let's stash it here, rather than prompting for it twice.
-        const keyCallback = (k) => (this.backupKey = k);
+        const keyCallback = (k: Uint8Array): void => {
+            this.backupKey = k;
+        };
 
         const { finished } = Modal.createDialog(
             RestoreKeyBackupDialog,
@@ -420,7 +422,7 @@ export default class CreateSecretStorageDialog extends React.PureComponent<IProp
         this.setState({ phase: Phase.ChooseKeyPassphrase });
     };
 
-    private onPassPhraseNextClick = async (e: React.FormEvent) => {
+    private onPassPhraseNextClick = async (e: React.FormEvent): Promise<void> => {
         e.preventDefault();
         if (!this.passphraseField.current) return; // unmounting
 
@@ -434,7 +436,7 @@ export default class CreateSecretStorageDialog extends React.PureComponent<IProp
         this.setState({ phase: Phase.PassphraseConfirm });
     };
 
-    private onPassPhraseConfirmNextClick = async (e: React.FormEvent) => {
+    private onPassPhraseConfirmNextClick = async (e: React.FormEvent): Promise<void> => {
         e.preventDefault();
 
         if (this.state.passPhrase !== this.state.passPhraseConfirm) return;

src/async-components/views/dialogs/security/ExportE2eKeysDialog.tsx

@@ -121,7 +121,7 @@ export default class ExportE2eKeysDialog extends React.Component<IProps, IState>
         return false;
     };
 
-    private onPassphraseChange = (ev: React.ChangeEvent<HTMLInputElement>, phrase: AnyPassphrase) => {
+    private onPassphraseChange = (ev: React.ChangeEvent<HTMLInputElement>, phrase: AnyPassphrase): void => {
         this.setState({
             [phrase]: ev.target.value,
         } as Pick<IState, AnyPassphrase>);

src/async-components/views/dialogs/security/ImportE2eKeysDialog.tsx

@@ -91,7 +91,7 @@ export default class ImportE2eKeysDialog extends React.Component<IProps, IState>
         return false;
     };
 
-    private startImport(file: File, passphrase: string) {
+    private startImport(file: File, passphrase: string): Promise<void> {
         this.setState({
             errStr: null,
             phase: Phase.Importing,