Refine Err propagation and avoid unwrap in transform closures (#4318)

Author: mingmwang

datafusion/core/src/physical_optimizer/coalesce_batches.rs

@@ -59,12 +59,12 @@ impl PhysicalOptimizerRule for CoalesceBatches {
                 || plan_any.downcast_ref::<HashJoinExec>().is_some()
                 || plan_any.downcast_ref::<RepartitionExec>().is_some();
             if wrap_in_coalesce {
-                Some(Arc::new(CoalesceBatchesExec::new(
+                Ok(Some(Arc::new(CoalesceBatchesExec::new(
                     plan.clone(),
                     target_batch_size,
-                )))
+                ))))
             } else {
-                None
+                Ok(None)
             }
         })
     }