refactor(sonar): replace if/throw with require/error

Sonar — replace hand-rolled 'throw IllegalArgumentException' / 'throw
IllegalStateException' with the idiomatic 'require { msg }' / 'error(msg)'.
Exception types preserved exactly (require throws IAE, error throws ISE).

amethyst/src/main/java/com/vitorpamplona/amethyst/model/nip30CustomEmojis/OwnedEmojiPacksState.kt

@@ -200,9 +200,7 @@ class OwnedEmojiPacksState(
         isPrivate: Boolean,
         account: Account,
     ) {
-        if (!EmojiUrlTag.isValidShortcode(emojiTag.code)) {
-            throw IllegalArgumentException("Invalid emoji shortcode: ${emojiTag.code}")
-        }
+        require(EmojiUrlTag.isValidShortcode(emojiTag.code)) { "Invalid emoji shortcode: ${emojiTag.code}" }
 
         val packEvent = getOwnedEmojiPackEvent(dTag) ?: return
 

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/components/WindowUtils.kt

@@ -52,7 +52,7 @@ tailrec fun Context.getActivity(): ComponentActivity =
     when (this) {
         is ComponentActivity -> this
         is ContextWrapper -> baseContext.getActivity()
-        else -> throw IllegalStateException("Requires a ComponentActivity to run")
+        else -> error("Requires a ComponentActivity to run")
     }
 
 fun Context.getActivityOrNull(): ComponentActivity? =