Need examples to show error case handling

[marcoscaceres]

With changing to extending stream, it's now non-obvious how to handle error cases.

The spec is lacking examples to show how to handle:

• disconnection
• timeout
• Fail to open - wrong path,
• Fail to open - device in use,
• Fail to open - nsufficient permissions,
• Fail to open - improper parameters (e.g. baud rate not supported by hardware)
• Buffer overflow / data lost due to reading too slowly

[JayBeavers]

Fail to open -- wrong path, device in use, insufficient permissions, improper parameters (e.g. baud rate not supported by hardware)

Buffer overflow / data lost due to reading too slowly

[marcoscaceres]

Oki, captured above as todo.

[reillyeon]

Examples are also needed for stream error conditions such as a break condition or parity error.