Print error messages in monitor/pubsub when errors occurs (#10050)

In monitor/pubsub mode, if the server closes the connection,
for example, use `CLIENT KILL`, redis-cli will exit directly
without printing any error messages.

This commit ensures that redis-cli will try to print the
error messages before exiting. Also there is a minor cleanup
for restart, see the example below.

before:
```
127.0.0.1:6379> monitor
OK
[root@ redis]#

127.0.0.1:6379> subscribe channel
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "channel"
3) (integer) 1
[root@ redis]#

127.0.0.1:6379> restart
127.0.0.1:6379> get keyUse 'restart' only in Lua debugging mode.
(nil)
```

after:
```
127.0.0.1:6379> monitor
OK
Error: Server closed the connection
[root@ redis]#

127.0.0.1:6379> subscribe channel
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "channel"
3) (integer) 1
Error: Server closed the connection
[root@ redis]#

127.0.0.1:6379> restart
Use 'restart' only in Lua debugging mode.
```

1 files changed, 10 insertions, 3 deletions

diff --git a/src/redis-cli.c b/src/redis-cli.c
index 94697f99f..0a19c025d 100644
--- a/src/redis-cli.c
+++ b/src/redis-cli.c
@@ -1415,7 +1415,10 @@ static int cliSendCommand(int argc, char **argv, long repeat) {
         redisAppendCommandArgv(context,argc,(const char**)argv,argvlen);
         if (config.monitor_mode) {
             do {
-                if (cliReadReply(output_raw) != REDIS_OK) exit(1);
+                if (cliReadReply(output_raw) != REDIS_OK) {
+                    cliPrintContextError();
+                    exit(1);
+                }
                 fflush(stdout);
 
                 /* This happens when the MONITOR command returns an error. */
@@ -1434,7 +1437,10 @@ static int cliSendCommand(int argc, char **argv, long repeat) {
             redisSetPushCallback(context, NULL);
 
             while (config.pubsub_mode) {
-                if (cliReadReply(output_raw) != REDIS_OK) exit(1);
+                if (cliReadReply(output_raw) != REDIS_OK) {
+                    cliPrintContextError();
+                    exit(1);
+                }
                 fflush(stdout); /* Make it grep friendly */
                 if (!config.pubsub_mode || config.last_cmd_type == REDIS_REPLY_ERROR) {
                     if (config.push_output) {
@@ -2271,7 +2277,8 @@ static void repl(void) {
                     linenoiseFree(line);
                     return; /* Return to evalMode to restart the session. */
                 } else {
-                    printf("Use 'restart' only in Lua debugging mode.");
+                    printf("Use 'restart' only in Lua debugging mode.\n");
+                    fflush(stdout);
                 }
             } else if (argc == 3 && !strcasecmp(argv[0],"connect")) {
                 sdsfree(config.conn_info.hostip);