Fix Compose Previews in the Reply sample

Currenly, Compose Previews don't support UIModeManager, so any previews
using the ContrastAwareReplyTheme will fail to render when trying to
apply contrast. While UIModeManager support is not added, we can work
around this issue by not adding contrast in Compose Previews.

Author: amaurymedeiros

Reply/app/src/main/java/com/example/reply/ui/theme/Theme.kt

@@ -30,6 +30,7 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.SideEffect
 import androidx.compose.ui.graphics.toArgb
 import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.platform.LocalInspectionMode
 import androidx.compose.ui.platform.LocalView
 import androidx.core.view.WindowCompat
 
@@ -269,7 +270,9 @@ fun isContrastAvailable(): Boolean {
 fun selectSchemeForContrast(isDark: Boolean,): ColorScheme {
     val context = LocalContext.current
     var colorScheme = if (isDark) darkScheme else lightScheme
-    if (isContrastAvailable()) {
+    val isPreview = LocalInspectionMode.current
+    // TODO(b/336693596): UIModeManager is not yet supported in preview
+    if (!isPreview && isContrastAvailable()) {
         val uiModeManager = context.getSystemService(Context.UI_MODE_SERVICE) as UiModeManager
         val contrastLevel = uiModeManager.contrast