Unable to update list element by index using CAS condition

cqlsh:test> CREATE TABLE cas_update(id int PRIMARY KEY,name text,friends list<text>);
cqlsh:test> INSERT INTO cas_update (id, name , friends ) VALUES ( 10,'John',['Paul','George']);
cqlsh:test> SELECT * FROM cas_update WHERE id=10;

 id | friends            | name
----+--------------------+------
 10 | ['Paul', 'George'] | John

cqlsh:test> UPDATE cas_update SET friends[0]='Helen' WHERE id=10 IF name='John';
Bad Request: List index 0 out of bound, list has size 0

cqlsh:test> UPDATE cas_update SET friends[0]='Helen' WHERE id=10;
cqlsh:test> SELECT * FROM cas_update WHERE id=10;

 id | friends             | name
----+---------------------+------
 10 | ['Helen', 'George'] | John

 ACHILLES_DML_STATEMENT@:writeDMLStatementLog Prepared statement : [INSERT INTO CompleteBean(id,followers,friends,name,preferences) VALUES (:id,:followers,:friends,:name,:preferences) USING TTL :ttl;] with CONSISTENCY LEVEL [ONE] 
 ACHILLES_DML_STATEMENT@:writeDMLStatementLog    bound values : [621309709026375591, [], [Paul, Andrew], John, {}, 0] 
 ACHILLES_DML_STATEMENT@:writeDMLStartBatch  
 ACHILLES_DML_STATEMENT@:writeDMLStartBatch  
 ACHILLES_DML_STATEMENT@:writeDMLStartBatch ****** BATCH UNLOGGED START ****** 
 ACHILLES_DML_STATEMENT@:writeDMLStartBatch  
 ACHILLES_DML_STATEMENT@:writeDMLStatementLog Parameterized statement : [UPDATE CompleteBean USING TTL 100 SET friends[0]=? WHERE id=621309709026375591 IF name=?;] with CONSISTENCY LEVEL [ONE] 
 ACHILLES_DML_STATEMENT@:writeDMLStatementLog    bound values : [100, 0, Helen, 621309709026375591, John] 
 ACHILLES_DML_STATEMENT@:writeDMLStatementLog Parameterized statement : [UPDATE CompleteBean USING TTL 100 SET friends[1]=null WHERE id=621309709026375591 IF name=?;] with CONSISTENCY LEVEL [ONE] 
 ACHILLES_DML_STATEMENT@:writeDMLStatementLog    bound values : [100, 1, null, 621309709026375591, John] 
 ACHILLES_DML_STATEMENT@:writeDMLEndBatch  
 ACHILLES_DML_STATEMENT@:writeDMLEndBatch   ****** BATCH UNLOGGED END with CONSISTENCY LEVEL [DEFAULT] ****** 
 ACHILLES_DML_STATEMENT@:writeDMLEndBatch  
 ACHILLES_DML_STATEMENT@:writeDMLEndBatch  
 ACHILLES_DML_STATEMENT@:truncateTable   Simple query : [TRUNCATE entity_with_enum] with CONSISTENCY LEVEL [ALL] 
 ACHILLES_DML_STATEMENT@:truncateTable   Simple query : [TRUNCATE CompleteBean] with CONSISTENCY LEVEL [ALL] 

com.datastax.driver.core.exceptions.InvalidQueryException: List index 0 out of bound, list has size 0
        at com.datastax.driver.core.exceptions.InvalidQueryException.copy(InvalidQueryException.java:35)
        at com.datastax.driver.core.DefaultResultSetFuture.extractCauseFromExecutionException(DefaultResultSetFuture.java:256)
        at com.datastax.driver.core.DefaultResultSetFuture.getUninterruptibly(DefaultResultSetFuture.java:172)
        at com.datastax.driver.core.AbstractSession.execute(AbstractSession.java:52)