fix Error struct export for asynk

[ayrat555]

There conflicts with blocking module's Error struct

15 | use fang::Error as FangError;
   |     ^^^^^^-----^^^^^^^^^^^^^
   |     |     |
   |     |     help: a similar name exists in the module: `error`
   |     no `Error` in the root

[pxp9]

Good job

[pxp9]

Good work