message_list: Fix misported blueslip.fatal call.

In fe66aef0ad, this call to
blueslip.fatal was ported incorrectly to `throw new Error` despite the
latter not supporting the extra_data parameter.

We address this by just doing blueslip logging with the extra data first.

Fixes #18273.

static/js/message_list.js

@@ -191,7 +191,8 @@ export class MessageList {
                 id,
                 items_length: this.data.num_items(),
             };
-            throw new Error("Cannot select id -1", error_data);
+            blueslip.error("Cannot select id -1", error_data);
+            throw new Error("Cannot select id -1");
         }
 
         id = closest_id;