Bug 1850796 - Handle preference icon nullability.

Preference getIcon method can now return a null Drawable.

app/src/main/java/org/mozilla/fenix/settings/account/AccountSettingsFragment.kt

@@ -142,9 +142,11 @@ class AccountSettingsFragment : PreferenceFragmentCompat() {
         preferenceSyncNow.apply {
             onPreferenceClickListener = getClickListenerForSyncNow()
 
-            icon = icon.mutate().apply {
+            icon?.let {
+                icon = it.mutate().apply {
                     setTint(context.getColorFromAttr(R.attr.textPrimary))
                 }
+            }
 
             // Current sync state
             if (requireComponents.backgroundServices.accountManager.isSyncActive()) {