Debugging Android Production Crashes Across 22 Apps: The System I Use

class MyApplication : Application() {

    override fun onCreate() {
        super.onCreate()
        initCrashlytics()
    }

    private fun initCrashlytics() {
        FirebaseCrashlytics.getInstance().apply {
            // Device context
            setCustomKey("device_model", Build.MODEL)
            setCustomKey("manufacturer", Build.MANUFACTURER)
            setCustomKey("os_version", Build.VERSION.RELEASE)
            setCustomKey("firmware", Build.DISPLAY)          // captures OEM build
            setCustomKey("sdk_int", Build.VERSION.SDK_INT.toString())

            // App context
            setCustomKey("app_version", BuildConfig.VERSION_NAME)
            setCustomKey("version_code", BuildConfig.VERSION_CODE.toString())
            setCustomKey("build_type", BuildConfig.BUILD_TYPE)

            // Session context
            setCustomKey("session_start", System.currentTimeMillis().toString())
            setCustomKey("install_source", getInstallSource())
        }
    }

    private fun getInstallSource(): String {
        return try {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
                packageManager.getInstallSourceInfo(packageName).installingPackageName
                    ?: "unknown"
            } else {
                @Suppress("DEPRECATION")
                packageManager.getInstallerPackageName(packageName) ?: "unknown"
            }
        } catch (e: Exception) {
            "error"
        }
    }
}

firmware

Build.DISPLAY

object CrashBreadcrumb {
    fun screen(name: String) {
        FirebaseCrashlytics.getInstance().log("SCREEN: $name")
    }

    fun action(name: String, params: Map<String, String> = emptyMap()) {
        val paramStr = if (params.isEmpty()) "" else " | ${params.entries.joinToString { "${it.key}=${it.value}" }}"
        FirebaseCrashlytics.getInstance().log("ACTION: $name$paramStr")
    }

    fun networkCall(endpoint: String, statusCode: Int) {
        FirebaseCrashlytics.getInstance().log("NETWORK: $endpoint → $statusCode")
    }

    fun state(key: String, value: String) {
        FirebaseCrashlytics.getInstance().setCustomKey("state_$key", value)
    }
}

@Composable
fun HomeScreen(viewModel: HomeViewModel = hiltViewModel()) {
    LaunchedEffect(Unit) {
        CrashBreadcrumb.screen("HomeScreen")
    }

    val uiState by viewModel.uiState.collectAsStateWithLifecycle()

    HomeContent(
        uiState = uiState,
        onRefresh = {
            CrashBreadcrumb.action("Refresh", mapOf("trigger" to "user"))
            viewModel.refresh()
        }
    )
}

SCREEN: HomeScreen
ACTION: Refresh | trigger=user
NETWORK: /api/items → 200
SCREEN: DetailScreen

Fatal Exception: java.lang.NullPointerException
  at com.sudarshantechlabs.myfamilytracker.data.repository.LocationRepository.processUpdate(LocationRepository.kt:87)
  at com.sudarshantechlabs.myfamilytracker.data.repository.LocationRepository$locationFlow$1.invokeSuspend(LocationRepository.kt:54)
  at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)

LocationRepository.processUpdate:87

LocationRepository.kt

// In LocationRepository, before the problematic operation:
CrashBreadcrumb.state("last_location_update", location?.toString() ?: "null")
CrashBreadcrumb.state("network_available", isNetworkAvailable.toString())
CrashBreadcrumb.state("background_state", isInBackground.toString())

// Add explicit state machine to track object lifecycle
class LocationRepository @Inject constructor(
    private val locationSource: LocationDataSource
) {
    private enum class RepositoryState { IDLE, COLLECTING, STOPPED }
    private var state = RepositoryState.IDLE

    fun processUpdate(location: Location?) {
        if (state != RepositoryState.COLLECTING) {
            // Log the unexpected call instead of crashing
            FirebaseCrashlytics.getInstance().log(
                "processUpdate called in state $state — ignoring"
            )
            return
        }
        // safe to proceed
        location ?: return // explicit null guard
        // ... process
    }
}

# Pseudocode — actual impl uses Firebase Admin SDK
def get_crash_rates(app_ids: list[str]) -> dict:
    return {
        app_id: crashlytics_client.get_crash_free_rate(
            app_id=app_id,
            period_days=1
        )
        for app_id in app_ids
    }

# Alert if any app drops below threshold
for app_id, rate in get_crash_rates(ALL_APP_IDS).items():
    if rate < 0.995:
        send_alert(f"{app_id}: crash-free rate {rate:.1%}")