Segfault in execute.c line 710

[ulm]

This version of bbe segfaults for me if I don't specify any command or specify an empty command (which is useful with the -s option). The released 0.2.2 version from sourceforce works fine.

The problem is in line 710 of execute.c:

        if (commands->block_start->letter == 'K') {

This misses a test for non-null commands->block_start.