[📚 docs] More details about error handling in the migration guide (#5787

)

* More details about error handling in the migration guide

* formating

docs/source/migration/4.0.mdx

@@ -25,7 +25,13 @@ We recommend using the plugin to automate the repetitive tasks but still go thro
 
 ## Error handling
 
-> ⚠️ Error handling changes are a behaviour change that is not be detected at compile time. Usages of `execute`, `toFlow` and `watch` must be updated to the new error handling or changed to their v3 compat equivalent.
+<Caution>
+Error handling changes are a behaviour change that is not detected at compile time. Usages of `execute`, `toFlow` and `watch` must be updated to the new error handling or changed to their v3 compat equivalent.
+
+See [`executeV3` and `toFlowV3`](#migration-helpers) for temporary methods to help with the migration.
+
+See [nullability](../advanced/nullability) for a quick peek at the future of GraphQL nullability and error handling.
+</Caution>
 
 ### Fetch errors do not throw