Enable lint rules for Promise handling to discourage misuse of them. (#2607)

* Enable lint rules for Promise handling to discourage misuse of them.
Squashed all of Hugh's commits into one.

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Co-authored-by: Hugh Nimmo-Smith <hughns@element.io>

src/settings/ProfileSettingsTab.tsx

@@ -8,6 +8,7 @@ Please see LICENSE in the repository root for full details.
 import { FC, useCallback, useEffect, useMemo, useRef } from "react";
 import { MatrixClient } from "matrix-js-sdk/src/client";
 import { useTranslation } from "react-i18next";
+import { logger } from "matrix-js-sdk/src/logger";
 
 import { useProfile } from "../profile/useProfile";
 import { FieldRow, InputField, ErrorMessage } from "../input/Input";
@@ -61,6 +62,8 @@ export const ProfileSettingsTab: FC<Props> = ({ client }) => {
           // @ts-ignore
           avatar: avatar && avatarSize > 0 ? avatar : undefined,
           removeAvatar: removeAvatar.current && (!avatar || avatarSize === 0),
+        }).catch((e) => {
+          logger.error("Failed to save profile", e);
         });
       }
     };