3006 VERIFY[S,U,P] and ASSERT[S,U,P] frequently check if first argument is zero

*** 161,171 ****
  {
          dsl_sync_task_t *dst;
          dsl_pool_t *dp = dstg->dstg_pool;
          uint64_t quota, used;
  
!         ASSERT3U(dstg->dstg_err, ==, 0);
  
          /*
           * Check for sufficient space.  We just check against what's
           * on-disk; we don't want any in-flight accounting to get in our
           * way, because open context may have already used up various
--- 161,171 ----
  {
          dsl_sync_task_t *dst;
          dsl_pool_t *dp = dstg->dstg_pool;
          uint64_t quota, used;
  
!         ASSERT0(dstg->dstg_err);
  
          /*
           * Check for sufficient space.  We just check against what's
           * on-disk; we don't want any in-flight accounting to get in our
           * way, because open context may have already used up various