Do not honor string power levels

src/TextForEvent.tsx

@@ -447,7 +447,8 @@ function textForPowerEvent(event): () => string | null {
         !event.getContent() || !event.getContent().users) {
         return null;
     }
-    const userDefault = event.getContent().users_default || 0;
+    const previousUserDefault = event.getPrevContent().users_default || 0;
+    const currentUserDefault = event.getContent().users_default || 0;
     // Construct set of userIds
     const users = [];
     Object.keys(event.getContent().users).forEach(
@@ -463,9 +464,16 @@ function textForPowerEvent(event): () => string | null {
     const diffs = [];
     users.forEach((userId) => {
         // Previous power level
-        const from = event.getPrevContent().users[userId];
+        let from = event.getPrevContent().users[userId];
+        if (!Number.isInteger(from)) {
+            from = previousUserDefault;
+        }
         // Current power level
-        const to = event.getContent().users[userId];
+        let to = event.getContent().users[userId];
+        if (!Number.isInteger(to)) {
+            to = currentUserDefault;
+        }
+        if (from === previousUserDefault && to === currentUserDefault) { return; }
         if (to !== from) {
             diffs.push({ userId, from, to });
         }
@@ -479,8 +487,8 @@ function textForPowerEvent(event): () => string | null {
         powerLevelDiffText: diffs.map(diff =>
             _t('%(userId)s from %(fromPowerLevel)s to %(toPowerLevel)s', {
                 userId: diff.userId,
-                fromPowerLevel: Roles.textualPowerLevel(diff.from, userDefault),
-                toPowerLevel: Roles.textualPowerLevel(diff.to, userDefault),
+                fromPowerLevel: Roles.textualPowerLevel(diff.from, previousUserDefault),
+                toPowerLevel: Roles.textualPowerLevel(diff.to, currentUserDefault),
             }),
         ).join(", "),
     });

src/components/views/settings/tabs/room/RolesRoomSettingsTab.tsx

@@ -284,6 +284,7 @@ export default class RolesRoomSettingsTab extends React.Component<IProps> {
             const mutedUsers = [];
 
             Object.keys(userLevels).forEach((user) => {
+                if (!Number.isInteger(userLevels[user])) { return; }
                 const canChange = userLevels[user] < currentUserLevel && canChangeLevels;
                 if (userLevels[user] > defaultUserLevel) { // privileged
                     privilegedUsers.push(