Fix command routing

use args[1] for firstKey instead of undefined so that commands are routed to the correct node instead of a random one.

Author: nfriedly

readme.md

@@ -137,16 +137,16 @@ follows:
 The raw command sending function varies from library to library; some are given
 below:
 
-| Library                                                            | Function                                                                              |
-| ------------------------------------------------------------------ | ------------------------------------------------------------------------------------- |
-| [`node-redis`](https://github.com/redis/node-redis)                | `async (...args: string[]) => client.sendCommand(args)`                               |
-| [`node-redis`](https://github.com/redis/node-redis) (cluster)      | `async (...args) => cluster.sendCommand(undefined, false, args)`                      |
-| [`ioredis`](https://github.com/luin/ioredis)                       | `async (command: string, ...args: string[]) => client.call(command, ...args)`         |
-| [`handy-redis`](https://github.com/mmkal/handy-redis)              | `async (...args: string[]) => client.nodeRedis.sendCommand(args)`                     |
-| [`tedis`](https://github.com/silkjs/tedis)                         | `async (...args: string[]) => client.command(...args)`                                |
-| [`redis-fast-driver`](https://github.com/h0x91b/redis-fast-driver) | `async (...args: string[]) => client.rawCallAsync(args)`                              |
-| [`yoredis`](https://github.com/djanowski/yoredis)                  | `async (...args: string[]) => (await client.callMany([args]))[0]`                     |
-| [`noderis`](https://github.com/wallneradam/noderis)                | `async (...args: string[]) => client.callRedis(...args)`                              |
+| Library                                                            | Function                                                                            |
+| ------------------------------------------------------------------ | ----------------------------------------------------------------------------------- |
+| [`node-redis`](https://github.com/redis/node-redis)                | `async (...args: string[]) => client.sendCommand(args)`                             |
+| [`node-redis`](https://github.com/redis/node-redis) (cluster)      | `async (...args) => cluster.sendCommand(args[1], false, args)`                      |
+| [`ioredis`](https://github.com/luin/ioredis)                       | `async (command: string, ...args: string[]) => client.call(command, ...args)`       |
+| [`handy-redis`](https://github.com/mmkal/handy-redis)              | `async (...args: string[]) => client.nodeRedis.sendCommand(args)`                   |
+| [`tedis`](https://github.com/silkjs/tedis)                         | `async (...args: string[]) => client.command(...args)`                              |
+| [`redis-fast-driver`](https://github.com/h0x91b/redis-fast-driver) | `async (...args: string[]) => client.rawCallAsync(args)`                            |
+| [`yoredis`](https://github.com/djanowski/yoredis)                  | `async (...args: string[]) => (await client.callMany([args]))[0]`                   |
+| [`noderis`](https://github.com/wallneradam/noderis)                | `async (...args: string[]) => client.callRedis(...args)`                            |
 
 #### `prefix`