look for places where we can flatten the control flow in a method by
exiting early with a throw, ie. instead of

   if (cond)
       stuff();
   else
       throw ex;

we  change it to:

   if (!cond)
      throw ex;
   stuff();

Change-Id: I8b6bdf883b325807c7e3a3ef698e4f4606e7d38b