Should not stop notifications/indications if not previously started

[twyatt]

For Peripheral.observe, when subscribers goes from 1 to 0, then underlying notifications/indications are stopped. Although this will also occur even if starting notifications/indications previously failed, or if connection drops. In both cases, stopping notifications/indications should not be attempted (the underlying BLE system will automatically clear notifications/indications).

Because these I/O operations are occurring when they shouldn't (aren't needed), the following exception is being thrown from the observe flow:

Caused by com.juul.kable.GattRequestRejectedException
       at com.juul.kable.PeripheralKt.setCharacteristicNotification(PeripheralKt.java:471)
       at com.juul.kable.PeripheralKt.access$setCharacteristicNotification(PeripheralKt.java:1)
       at com.juul.kable.AndroidPeripheral.stopObservation$core_release(AndroidPeripheral.java:391)
       at com.juul.kable.AndroidPeripheral$stopObservation$1.invokeSuspend(AndroidPeripheral.java:12)
       at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(BaseContinuationImpl.java:33)
       at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.java:104)
       at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.java:571)
       at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask(CoroutineScheduler.java:750)
       at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker(CoroutineScheduler.java:678)
       at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.java:665)

[twyatt]

A potential fix is available as a SNAPSHOT build (from #193):

repositories {
    maven("https://oss.sonatype.org/content/repositories/snapshots")
}

dependencies {
    implementation("com.juul.kable:core:0.10.3-issue-190-3-SNAPSHOT")
}

[ln-12]

Looks good in my use case, thanks :)

[twyatt]

On an internal project, noticed that some BLE connections stalled after app was in the background for a long period of time (with device coming in and out of range).

Not sure if it is a regression due to the changes in the SNAPSHOT mentioned above, but I'm going to do more testing before merging #193.