Drop should never panic; remove unwrap from SpiDriver Drop

[MartinBroers]

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Pull Request Details 📖

Description

In rust, we should never crash in a Drop implementation. The unwrap in the SpiDriver Drop implementation causes a crash when the SPI is not correctly initialized (in my case, when initializing the W5500 ethernet peripheral, the spi device is partially initialized, but the ethernet driver unwraps when it encounters an error calling this Drop).

So I changed the unwrap into an error log. I am not sure though how exactly we should handle this. So I am open to changing this :)

Testing

I have tested this with an ESP without W55000 connected and happy flow with one connected.

[ivmarkov]

@MartinBroers Thanks for this PR.

I suggest to turn the PR the other way around:

• If the SPI Driver cannot be initialized correctly, its new constructor should return an error, by also properly disposing all C driver resources.

We should not allow partially initialized driver in the first place, which is the crux of the issue.