Broken "help" command on cqlsh 6.0.0

On cqlsh 5.0.1, "help select" command prints this:

cqlsh> help select
*** No browser to display CQL help. URL for help topic select : https://cassandra.apache.org/doc/cql3/CQL-3.2.html#selectStmt

However, on cqlsh 6.0.0, "help select" command prints this:

cqlsh> help select
object of type 'NoneType' has no len()

Steps to reproduce:

1. Create and start a Cassandra 4 docker container

   ~ $ docker create --name cassandra4 cassandra:4.0
   ~ $ docker start cassandra4

2. Get a shell inside the docker container

    docker exec -ti CONTAINER_NAME bash

3. Start a cqlsh and run the "help" command inside it (you have to wait for the Cassandra server starting, I had to run "nodetool enablebinary" too, not sure why)

   root@b03a20987964:/# cqlsh
   Connected to Test Cluster at 127.0.0.1:9042
   [cqlsh 6.0.0 | Cassandra 4.0-rc1 | CQL spec 3.4.5 | Native protocol v5]
   Use HELP for help.
   cqlsh> help select
   object of type 'NoneType' has no len()
   cqlsh>