fix: call CLIENT INFO from redis module will crash the server (#8560)

Because when the RM_Call is invoked. It will create a faker client.
The point is client connection is NULL, so server will crash in connGetInfo

Co-authored-by: Viktor Söderqvist <viktor.soderqvist@est.tech>

src/connection.c

@@ -427,7 +427,7 @@ int connGetState(connection *conn) {
  * For sockets, we always return "fd=<fdnum>" to maintain compatibility.
  */
 const char *connGetInfo(connection *conn, char *buf, size_t buf_len) {
-    snprintf(buf, buf_len-1, "fd=%i", conn->fd);
+    snprintf(buf, buf_len-1, "fd=%i", conn == NULL ? -1 : conn->fd);
     return buf;
 }
 

tests/unit/moduleapi/misc.tcl

@@ -111,4 +111,8 @@ start_server {tags {"modules"}} {
         r test.log_tsctx "info" "Test message"
         verify_log_message 0 "*<misc> Test message*" 0
     }
+
+    test {test RM_Call CLIENT INFO} {
+        assert_match "*fd=-1*" [r test.call_generic client info]
+    }
 }