sstables: convert assert to exception
sstables: convert assert to exception

Signed-off-by: Glauber Costa <f8b79557d19b40666ebe336545a0b6178af65685@cloudius-systems.com>

senseb/scylla,stamhe/scylla,bowlofstew/scylla,wildinto/scylla,shaunstanislaus/scylla,kangkot/scylla,aruanruan/scylla,dwdm/scylla,duarten/scylla,justintung/scylla,senseb/scylla,capturePointer/scylla,gwicke/scylla,duarten/scylla,wildinto/scylla,raphaelsc/scylla,raphaelsc/scylla,aruanruan/scylla,scylladb/scylla,kjniemi/scylla,rluta/scylla,shaunstanislaus/scylla,acbellini/scylla,justintung/scylla,raphaelsc/scylla,phonkee/scylla,avikivity/scylla,asias/scylla,scylladb/scylla,victorbriz/scylla,respu/scylla,linearregression/scylla,glommer/scylla,wildinto/scylla,kjniemi/scylla,gwicke/scylla,avikivity/scylla,scylladb/scylla,asias/scylla,guiquanz/scylla,gwicke/scylla,stamhe/scylla,glommer/scylla,capturePointer/scylla,phonkee/scylla,victorbriz/scylla,dwdm/scylla,bowlofstew/scylla,acbellini/scylla,dwdm/scylla,duarten/scylla,linearregression/scylla,kjniemi/scylla,glommer/scylla,respu/scylla,eklitzke/scylla,rentongzhang/scylla,rluta/scylla,rentongzhang/scylla,capturePointer/scylla,senseb/scylla,rluta/scylla,linearregression/scylla,eklitzke/scylla,guiquanz/scylla,aruanruan/scylla,asias/scylla,shaunstanislaus/scylla,kangkot/scylla,phonkee/scylla,rentongzhang/scylla,tempbottle/scylla,guiquanz/scylla,justintung/scylla,kangkot/scylla,avikivity/scylla,victorbriz/scylla,eklitzke/scylla,respu/scylla,tempbottle/scylla,stamhe/scylla,scylladb/scylla,acbellini/scylla,bowlofstew/scylla,tempbottle/scylla