1 files changed, 3 insertions, 3 deletions
diff --git a/src/client/views/animationtimeline/TimelineOverview.tsx b/src/client/views/animationtimeline/TimelineOverview.tsx
index 82ac69a3b..489c4dcde 100644
--- a/src/client/views/animationtimeline/TimelineOverview.tsx
+++ b/src/client/views/animationtimeline/TimelineOverview.tsx
@@ -28,14 +28,14 @@ export class TimelineOverview extends React.Component<TimelineOverviewProps> {
     @observable private overviewBarWidth: number = 0;
     @observable private playbarWidth: number = 0;
     @observable private activeOverviewWidth: number = 0;
-    @observable private _authoringReaction?: IReactionDisposer;
+    @observable private _authoringReaction?: IReactionDisposer = undefined;
     @observable private visibleTime: number = 0;
     @observable private currentX: number = 0;
     @observable private visibleStart: number = 0;
     private readonly DEFAULT_HEIGHT = 50;
     private readonly DEFAULT_WIDTH = 300;
 
-    componentDidMount = () => {
+    componentDidMount() {
         this.setOverviewWidth();
 
         this._authoringReaction = reaction(
@@ -48,7 +48,7 @@ export class TimelineOverview extends React.Component<TimelineOverviewProps> {
                 }
             }
         );
-    };
+    }
 
     componentWillUnmount = () => {
         this._authoringReaction && this._authoringReaction();