Strictify Timeline Panel (#11165)

* Get initial fix working

* add a couple of union types to tidy up a bit

Author: artcodespace

src/components/structures/TimelinePanel.tsx

@@ -591,6 +591,8 @@ class TimelinePanel extends React.Component<IProps, IState> {
         const dir = backwards ? EventTimeline.BACKWARDS : EventTimeline.FORWARDS;
         const canPaginateKey = backwards ? "canBackPaginate" : "canForwardPaginate";
         const paginatingKey = backwards ? "backPaginating" : "forwardPaginating";
+        type CanPaginateKey = typeof canPaginateKey;
+        type PaginatingKey = typeof paginatingKey;
 
         if (!this.state[canPaginateKey]) {
             debuglog("have given up", dir, "paginating this timeline");
@@ -599,7 +601,7 @@ class TimelinePanel extends React.Component<IProps, IState> {
 
         if (!this.timelineWindow?.canPaginate(dir)) {
             debuglog("can't", dir, "paginate any further");
-            this.setState({ [canPaginateKey]: false } as Pick<IState, typeof canPaginateKey>);
+            this.setState({ [canPaginateKey]: false } as Pick<IState, CanPaginateKey>);
             return Promise.resolve(false);
         }
 
@@ -609,7 +611,7 @@ class TimelinePanel extends React.Component<IProps, IState> {
         }
 
         debuglog("Initiating paginate; backwards:" + backwards);
-        this.setState({ [paginatingKey]: true } as Pick<IState, typeof paginatingKey>);
+        this.setState({ [paginatingKey]: true } as Pick<IState, PaginatingKey>);
 
         return this.onPaginationRequest(this.timelineWindow, dir, PAGINATE_SIZE).then(async (r) => {
             if (this.unmounted) {
@@ -624,13 +626,13 @@ class TimelinePanel extends React.Component<IProps, IState> {
 
             const { events, liveEvents, firstVisibleEventIndex } = this.getEvents();
             this.buildLegacyCallEventGroupers(events);
-            const newState: Partial<IState> = {
+            const newState = {
                 [paginatingKey]: false,
                 [canPaginateKey]: r,
                 events,
                 liveEvents,
                 firstVisibleEventIndex,
-            };
+            } as Pick<IState, PaginatingKey | CanPaginateKey | "events" | "liveEvents" | "firstVisibleEventIndex">;
 
             // moving the window in this direction may mean that we can now
             // paginate in the other where we previously could not.
@@ -647,7 +649,7 @@ class TimelinePanel extends React.Component<IProps, IState> {
             // has in memory because we never gave the component a chance to scroll
             // itself into the right place
             return new Promise((resolve) => {
-                this.setState<null>(newState, () => {
+                this.setState(newState, () => {
                     // we can continue paginating in the given direction if:
                     // - timelineWindow.paginate says we can
                     // - we're paginating forwards, or we won't be trying to