Replace newTranslatableError with UserFriendlyError (#10440

* Introduce UserFriendlyError

* Replace newTranslatableError with UserFriendlyError

* Remove ITranslatableError

* Fix up some strict lints

* Document when we/why we can remove

* Update matrix-web-i18n

Includes changes to find `new UserFriendlyError`,
see https://github.com/matrix-org/matrix-web-i18n/pull/6

* Include room ID in error

* Translate fallback error

* Translate better

* Update i18n strings

* Better re-use

* Minor comment fixes

src/@types/global.d.ts

@@ -187,6 +187,11 @@ declare global {
     }
 
     interface Error {
+        // Standard
+        // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error/cause
+        cause?: unknown;
+
+        // Non-standard
         // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error/fileName
         fileName?: string;
         // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error/lineNumber
@@ -195,6 +200,22 @@ declare global {
         columnNumber?: number;
     }
 
+    // We can remove these pieces if we ever update to `target: "es2022"` in our
+    // TypeScript config which supports the new `cause` property, see
+    // https://github.com/vector-im/element-web/issues/24913
+    interface ErrorOptions {
+        // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error/cause
+        cause?: unknown;
+    }
+
+    interface ErrorConstructor {
+        new (message?: string, options?: ErrorOptions): Error;
+        (message?: string, options?: ErrorOptions): Error;
+    }
+
+    // eslint-disable-next-line no-var
+    var Error: ErrorConstructor;
+
     // https://github.com/microsoft/TypeScript/issues/28308#issuecomment-650802278
     interface AudioWorkletProcessor {
         readonly port: MessagePort;