Fix the LCD library's handling of errors.

Doesn't seem to be compatible with anyhow, so I can't use the `?` syntactic sugar.

```
the trait bound `hd44780_driver::error::Error: std::error::Error` is not satisfied
the following other types implement trait `FromResidual`:
as FromResidual>>
as FromResidual>>
required for `anyhow::Error` to implement `From`
required for `Result<(), anyhow::Error>` to implement `FromResidual>` [E0277]
```