remember any room avatars set on matrix-side

matrix/api.js

@@ -167,6 +167,8 @@ async function profileSetAvatarUrl(mxid, avatar_url) {
  * @param {number} power
  */
 async function setUserPower(roomID, mxid, power) {
+	assert(roomID[0] === "!")
+	assert(mxid[0] === "@")
 	// Yes it's this hard https://github.com/matrix-org/matrix-appservice-bridge/blob/2334b0bae28a285a767fe7244dad59f5a5963037/src/components/intent.ts#L352
 	const powerLevels = await getStateEvent(roomID, "m.room.power_levels", "")
 	const users = powerLevels.users || {}