[lora-sx126x,lora-sx127x]: Add dependencies for sync/async modems.

[brenordv]

Problem

When installing lora-sx126x or lora-sx127x packages via mip, users will generally install only one of them (either SyncModem or AsyncModem wrapper classes), and this can lead to runtime errors.

When handling import in lora/__init__.py, an ImportError would can be incorrectly raised when the error message contained lib.lora instead of just lora.

I noticed this after installing the lora-sx1262 package via Thonny package manager.

Solution

To fix the import problem, I added an extra check to prevent this from happening by checking if the error message contains both "no module named", and "lora". Since the check was the same for all imports, I centralized the check in a function.

Testing

Install the package and verify the modem classes are available:

import mip
mip.install("lora-sx126x")
from lora import SX1262, AsyncSX1262  # Should work now

[projectgus]

Hi @brenordv,

Thanks for digging into this and submitting this PR. Not depending on either lora-sync or lora-async is an intentional design choice to save flash size - both these packages are biggish and no one is likely to need both.

We tried to smooth over the usability of this in the installation instructions and by producing a helpful error message if neither package was installed. It seems like your PR also fixes a case where that message wasn't being generated, thanks!

[projectgus]

@brenordv Thanks for updating the PR.

Maybe I wasn't clear enough in my review: I'm happy to improve the error reporting if both lora-sync and lora-async aren't installed (thanks for that fix).

However, adding both packages as dependencies by default will increase the code size impact of using lora significantly (and almost no one will use both the sync and async APIs on the same board). I'm not inclined to make this change, unless can be convinced it's too difficult to use otherwise.

[brenordv]

@brenordv Thanks for updating the PR.

Maybe I wasn't clear enough in my review: I'm happy to improve the error reporting if both lora-sync and lora-async aren't installed (thanks for that fix).

However, adding both packages as dependencies by default will increase the code size impact of using lora significantly (and almost no one will use both the sync and async APIs on the same board). I'm not inclined to make this change, unless can be convinced it's too difficult to use otherwise.

@projectgus 💯! That makes perfect sense. Come to think of it, I can't see a scenario where you would need both running at the same time. I trimmed it down just to the error message treatment.

[projectgus]

Thanks @brenordv!

[projectgus]

(Tossed up whether to bump the bugfix version of the package on this, but as it's only a problem for imports it didn't seem worth updating existing installs.)