Merge pull request #4856 from matrix-org/t3chguy/fix-join-slashcmd

Fix /join slash command via servers including room id as a via

src/SlashCommands.tsx

@@ -495,8 +495,7 @@ export const Commands = [
                     });
                     return success();
                 } else if (params[0][0] === '!') {
-                    const roomId = params[0];
-                    const viaServers = params.splice(0);
+                    const [roomId, ...viaServers] = params;
 
                     dis.dispatch({
                         action: 'view_room',