fix: remove crash-risk !! operators in UnitPrefs and MainViewModel

UnitPrefs: getString() returns String? even with a non-null default,
so !! crashes on corrupted prefs. Replaced with explicit elvis fallback
to the same enum default.

MainViewModel: forecastResult.getOrThrow() is logically safe (when-branch
guards it) but unnecessarily brittle. Replaced with getOrNull() ?: emptyList().

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

2 files changed, 5 insertions, 5 deletions

diff --git a/android-app/app/src/main/kotlin/org/terst/nav/UnitPrefs.kt b/android-app/app/src/main/kotlin/org/terst/nav/UnitPrefs.kt
index 8d60ae0..c0745f8 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/UnitPrefs.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/UnitPrefs.kt
@@ -17,19 +17,19 @@ class UnitPrefs(context: Context) {
     private val prefs = context.getSharedPreferences("unit_prefs", Context.MODE_PRIVATE)
 
     var tempUnit: TempUnit
-        get() = TempUnit.valueOf(prefs.getString(KEY_TEMP, TempUnit.FAHRENHEIT.name)!!)
+        get() = TempUnit.valueOf(prefs.getString(KEY_TEMP, null) ?: TempUnit.FAHRENHEIT.name)
         set(v) { prefs.edit().putString(KEY_TEMP, v.name).apply() }
 
     var depthUnit: DepthUnit
-        get() = DepthUnit.valueOf(prefs.getString(KEY_DEPTH, DepthUnit.FEET.name)!!)
+        get() = DepthUnit.valueOf(prefs.getString(KEY_DEPTH, null) ?: DepthUnit.FEET.name)
         set(v) { prefs.edit().putString(KEY_DEPTH, v.name).apply() }
 
     var pressureUnit: PressureUnit
-        get() = PressureUnit.valueOf(prefs.getString(KEY_PRESSURE, PressureUnit.HPA.name)!!)
+        get() = PressureUnit.valueOf(prefs.getString(KEY_PRESSURE, null) ?: PressureUnit.HPA.name)
         set(v) { prefs.edit().putString(KEY_PRESSURE, v.name).apply() }
 
     var speedUnit: SpeedUnit
-        get() = SpeedUnit.valueOf(prefs.getString(KEY_SPEED, SpeedUnit.KNOTS.name)!!)
+        get() = SpeedUnit.valueOf(prefs.getString(KEY_SPEED, null) ?: SpeedUnit.KNOTS.name)
         set(v) { prefs.edit().putString(KEY_SPEED, v.name).apply() }
 
     fun formatTemp(tempC: Double): String = when (tempUnit) {
diff --git a/android-app/app/src/main/kotlin/org/terst/nav/ui/MainViewModel.kt b/android-app/app/src/main/kotlin/org/terst/nav/ui/MainViewModel.kt
index 57de608..c648fab 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/ui/MainViewModel.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/ui/MainViewModel.kt
@@ -315,7 +315,7 @@ class MainViewModel(
                 }
                 else -> {
                     _windArrow.value = arrowResult.getOrNull()
-                    _forecast.value  = forecastResult.getOrThrow()
+                    _forecast.value  = forecastResult.getOrNull() ?: emptyList()
                     _uiState.value   = UiState.Success
                 }
             }