Is there a detailed description of the err parameter type in the callback function？

[xuruijing]

Many callback functions in the API have the err parameter, where is the type of this parameter described in detail? For example, hashcode does not exist or timeout error messages

[alanshaw]

err objects are currently just the built in type Error. There is discussion and work in progress for adding error codes to messages so that they can be dealt with appropriately: https://github.com/ipfs/interface-ipfs-core/issues/300