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/components/views/right_panel/UserInfo.tsx

@@ -34,7 +34,7 @@ import { DeviceInfo } from "matrix-js-sdk/src/crypto/deviceinfo";
 
 import dis from "../../../dispatcher/dispatcher";
 import Modal from "../../../Modal";
-import { _t } from "../../../languageHandler";
+import { _t, UserFriendlyError } from "../../../languageHandler";
 import DMRoomMap from "../../../utils/DMRoomMap";
 import AccessibleButton, { ButtonEvent } from "../elements/AccessibleButton";
 import SdkConfig from "../../../SdkConfig";
@@ -448,7 +448,15 @@ export const UserOptionsSection: React.FC<{
                     const inviter = new MultiInviter(roomId || "");
                     await inviter.invite([member.userId]).then(() => {
                         if (inviter.getCompletionState(member.userId) !== "invited") {
-                            throw new Error(inviter.getErrorText(member.userId) ?? undefined);
+                            const errorStringFromInviterUtility = inviter.getErrorText(member.userId);
+                            if (errorStringFromInviterUtility) {
+                                throw new Error(errorStringFromInviterUtility);
+                            } else {
+                                throw new UserFriendlyError(
+                                    `User (%(user)s) did not end up as invited to %(roomId)s but no error was given from the inviter utility`,
+                                    { user: member.userId, roomId, cause: undefined },
+                                );
+                            }
                         }
                     });
                 } catch (err) {