Guard translation methods with typescript to protect against invalid usage (#26021)

src/languageHandler.tsx

@@ -0,0 +1,66 @@
+/*
+Copyright 2023 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import React from "react";
+import {
+    IVariables,
+    TranslatedString,
+    TranslationKey as ReactTranslationKey,
+    // eslint-disable-next-line camelcase
+    _t as react_t,
+    // eslint-disable-next-line camelcase
+    _td as react_td,
+    // eslint-disable-next-line camelcase
+    _tDom as react_tDom,
+    Tags,
+    UserFriendlyError as ReactUserFriendlyError,
+    ErrorOptions,
+} from "matrix-react-sdk/src/languageHandler";
+import { Leaves } from "matrix-react-sdk/src/@types/common";
+
+import type ReactEN from "matrix-react-sdk/src/i18n/strings/en_EN.json";
+import type EN from "./i18n/strings/en_EN.json";
+
+/**
+ * This module wraps languageHandler in the matrix-react-sdk and adds type casts to include translations
+ * which we know will be injected by webpack.
+ */
+
+export type TranslationKey = Leaves<typeof EN & typeof ReactEN, "|", string | { other: string }>;
+
+export class UserFriendlyError extends ReactUserFriendlyError {
+    public constructor(message: TranslationKey, substitutionVariablesAndCause?: IVariables & ErrorOptions) {
+        super(message as ReactTranslationKey, substitutionVariablesAndCause);
+    }
+}
+
+export function _td(s: TranslationKey): TranslationKey {
+    return react_td(s as ReactTranslationKey);
+}
+
+// eslint-next-line @typescript-eslint/naming-convention
+export function _t(text: TranslationKey, variables?: IVariables): string;
+export function _t(text: TranslationKey, variables: IVariables | undefined, tags: Tags): React.ReactNode;
+export function _t(text: TranslationKey, variables?: IVariables, tags?: Tags): TranslatedString {
+    return react_t(text as ReactTranslationKey, variables, tags!);
+}
+
+// eslint-next-line @typescript-eslint/naming-convention
+export function _tDom(text: TranslationKey, variables?: IVariables): TranslatedString;
+export function _tDom(text: TranslationKey, variables: IVariables, tags: Tags): React.ReactNode;
+export function _tDom(text: TranslationKey, variables?: IVariables, tags?: Tags): TranslatedString {
+    return react_tDom(text as ReactTranslationKey, variables!, tags!);
+}