Check for missing event_id in send_event response

because it is an optional field as of MSC4157

Author: AndrewFerr

src/embedded.ts

@@ -300,6 +300,9 @@ export class RoomWidgetClient extends MatrixClient {
         }
 
         room.updatePendingEvent(event, EventStatus.SENT, response.event_id);
+        if (!response.event_id) {
+            throw new Error("'event_id' absent from response to an event request");
+        }
         return { event_id: response.event_id };
     }
 
@@ -309,7 +312,11 @@ export class RoomWidgetClient extends MatrixClient {
         content: any,
         stateKey = "",
     ): Promise<ISendEventResponse> {
-        return await this.widgetApi.sendStateEvent(eventType, stateKey, content, roomId);
+        const response = await this.widgetApi.sendStateEvent(eventType, stateKey, content, roomId);
+        if (response.event_id === undefined) {
+            throw new Error("'event_id' absent from response to an event request");
+        }
+        return { event_id: response.event_id };
     }
 
     /**