[Android] Fix exceptions seen in the wild in v1.9.9.2

[VanceVagell]

Here's the latest batch of exceptions in Google Play Developer Console seen by users in the wild in v1.9.9.2. We're in MUCH better shape as of that release in terms of exceptions, but these are still being seen by >10 users from time to time and should be fixed as well.

Exception java.lang.NullPointerException:
at com.vagell.kv4pht.ui.MainActivity.tuneToMemoryUi (MainActivity.java:1321)
at com.vagell.kv4pht.ui.MainActivity.lambda$onActivityResult$20$com-vagell-kv4pht-ui-MainActivity (MainActivity.java:1812)
at com.vagell.kv4pht.ui.MainActivity$$ExternalSyntheticLambda23.run (D8$$SyntheticClass)
at android.os.Handler.handleCallback (Handler.java:958)
at android.os.Handler.dispatchMessage (Handler.java:99)
at android.os.Looper.loopOnce (Looper.java:207)
at android.os.Looper.loop (Looper.java:296)
at android.app.ActivityThread.main (ActivityThread.java:8227)
at java.lang.reflect.Method.invoke
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:576)
at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:1049)

Exception java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.String.trim()' on a null object reference
at jdk.internal.math.FloatingDecimal.readJavaFormatString (FloatingDecimal.java:1838)
at jdk.internal.math.FloatingDecimal.parseFloat (FloatingDecimal.java:122)
at java.lang.Float.parseFloat (Float.java:558)
at com.vagell.kv4pht.radio.RadioAudioService.updateFrequencyLimitsForBand (RadioAudioService.java:946)
at com.vagell.kv4pht.ui.MainActivity.applyTxFreqLimitsSettings (MainActivity.java:997)
at com.vagell.kv4pht.ui.MainActivity.lambda$applySettings$3$com-vagell-kv4pht-ui-MainActivity (MainActivity.java:939)
at com.vagell.kv4pht.ui.MainActivity$$ExternalSyntheticLambda14.run (D8$$SyntheticClass)
at android.os.Handler.handleCallback (Handler.java:958)
at android.os.Handler.dispatchMessage (Handler.java:99)
at android.os.Looper.loopOnce (Looper.java:205)
at android.os.Looper.loop (Looper.java:294)
at android.app.ActivityThread.main (ActivityThread.java:8261)
at java.lang.reflect.Method.invoke
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:622)
at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:977)

Exception java.lang.NullPointerException:
at com.vagell.kv4pht.radio.RadioAudioService.setMode (RadioAudioService.java:391)
at com.vagell.kv4pht.ui.MainActivity.startFirmwareActivity (MainActivity.java:1858)
at com.vagell.kv4pht.ui.MainActivity.access$4000 (MainActivity.java:110)
at com.vagell.kv4pht.ui.MainActivity$20.onClick (MainActivity.java:1628)
at com.google.android.material.snackbar.Snackbar.lambda$setAction$0$com-google-android-material-snackbar-Snackbar (Snackbar.java:357)
at com.google.android.material.snackbar.Snackbar$$ExternalSyntheticLambda0.onClick (D8$$SyntheticClass)
at android.view.View.performClick (View.java:8508)
at android.widget.TextView.performClick (TextView.java:18631)
at com.google.android.material.button.MaterialButton.performClick (MaterialButton.java:1218)
at android.view.View.performClickInternal (View.java:8485)
at android.view.View.-$$Nest$mperformClickInternal (Unknown Source)
at android.view.View$PerformClick.run (View.java:33213)
at android.os.Handler.handleCallback (Handler.java:995)
at android.os.Handler.dispatchMessage (Handler.java:103)
at android.os.Looper.loopOnce (Looper.java:273)
at android.os.Looper.loop (Looper.java:363)
at android.app.ActivityThread.main (ActivityThread.java:10060)
at java.lang.reflect.Method.invoke
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:632)
at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:975)

Exception java.lang.RuntimeException:
at android.app.LoadedApk$ReceiverDispatcher$Args.lambda$getRunnable$0 (LoadedApk.java:1989)
at android.app.LoadedApk$ReceiverDispatcher$Args.$r8$lambda$mcNAAl1SQ4MyJPyDg8TJ2x2h0Rk (Unknown Source)
at android.app.LoadedApk$ReceiverDispatcher$Args$$ExternalSyntheticLambda0.run (D8$$SyntheticClass)
at android.os.Handler.handleCallback (Handler.java:995)
at android.os.Handler.dispatchMessage (Handler.java:103)
at android.os.Looper.loopOnce (Looper.java:273)
at android.os.Looper.loop (Looper.java:363)
at android.app.ActivityThread.main (ActivityThread.java:10060)
at java.lang.reflect.Method.invoke
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:632)
at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:975)
Caused by java.util.concurrent.RejectedExecutionException:
at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution (ThreadPoolExecutor.java:2100)
at java.util.concurrent.ThreadPoolExecutor.reject (ThreadPoolExecutor.java:851)
at java.util.concurrent.ThreadPoolExecutor.execute (ThreadPoolExecutor.java:1389)
at com.vagell.kv4pht.ui.MainActivity.tuneToMemoryUi (MainActivity.java:1329)
at com.vagell.kv4pht.ui.MainActivity.setScanningUi (MainActivity.java:1705)
at com.vagell.kv4pht.ui.MainActivity.access$300 (MainActivity.java:110)
at com.vagell.kv4pht.ui.MainActivity$21.onReceive (MainActivity.java:1656)
at android.app.LoadedApk$ReceiverDispatcher$Args.lambda$getRunnable$0 (LoadedApk.java:1981)