fix: prevent segfault on Linux if device isn't opened

[AsCress]

Fixes #2926

Summary by Sourcery

Prevent segmentation fault on Linux by verifying that the USB device opens successfully before configuring it

Bug Fixes:

• Check the result of mDevice.open() in DesktopUSBCommunicationHandler and return early if it fails to prevent segfault on Linux
• Log an error when opening the USB device fails

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

The pull request enhances the USB communication handler by checking the result of the device open operation and aborting further setup if opening the device fails, preventing potential segfaults on Linux.

Sequence diagram for improved device opening in USB communication handler

sequenceDiagram
participant Handler as DesktopUSBCommunicationHandler
participant Device as UsbSerialDevice
participant Logger
Handler->>Device: open()
alt Device fails to open
Device-->>Handler: false
Handler->>Logger: e("Failed to open device")
Handler-->>Handler: return (abort setup)
else Device opens successfully
Device-->>Handler: true
Handler->>Device: setBaudRate(1000000)
Handler->>Device: setDataBits(dataBits8)
Handler->>Device: setStopBits(stopBits1)
end

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File-Level Changes

Change	Details	Files
Added conditional handling for opening the USB device	Replaced unconditional device.open() call with an if check on its boolean result Logged an error when device.open() returns false Returned early from the method if device open fails to avoid subsequent calls	lib/communication/handler/desktop_comms_handler.dart

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[sourcery-ai]

Hey there - I've reviewed your changes and they look great!

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[github-actions]

Build Status

Build successful. APKs to test: https://github.com/fossasia/pslab-app/actions/runs/17850626378/artifacts/4053354979.

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[mariobehling]

Is there an issue about this, which one? Please stick to best practices https://blog.fossasia.org/open-source-developer-guide-and-best-practices-at-fossasia/

[AsCress]

@mariobehling #2926