Update gesture initialization

Author: j-piasecki

android/src/main/java/com/swmansion/gesturehandler/core/GestureHandler.kt

@@ -817,7 +817,11 @@ open class GestureHandler<ConcreteGestureHandlerT : GestureHandler<ConcreteGestu
   abstract class Factory<T : GestureHandler<T>> {
     abstract val type: Class<T>
     abstract val name: String
-    abstract fun create(context: Context?): T
+
+    protected abstract fun create(context: Context?): T
+
+    fun create(context: Context?, handlerTag: Int): T = create(context).also { it.tag = handlerTag }
+
     open fun setConfig(handler: T, config: ReadableMap) {
       handler.resetConfig()
       if (config.hasKey(KEY_SHOULD_CANCEL_WHEN_OUTSIDE)) {

android/src/main/java/com/swmansion/gesturehandler/react/RNGestureHandlerModule.kt

@@ -41,10 +41,8 @@ class RNGestureHandlerModule(reactContext: ReactApplicationContext?) :
     val handlerFactory = RNGestureHandlerFactoryUtil.findFactoryForName<T>(handlerName)
       ?: throw JSApplicationIllegalArgumentException("Invalid handler name $handlerName")
 
-    val handler = handlerFactory.create(reactApplicationContext).apply {
-      tag = handlerTag
-      setOnTouchEventListener(eventDispatcher)
-    }
+    val handler = handlerFactory.create(reactApplicationContext, handlerTag)
+    handler.setOnTouchEventListener(eventDispatcher)
     registry.registerHandler(handler)
     interactionManager.configureInteractions(handler, config)
     handlerFactory.setConfig(handler, config)
@@ -77,13 +75,11 @@ class RNGestureHandlerModule(reactContext: ReactApplicationContext?) :
 
   @Suppress("UNCHECKED_CAST")
   private fun <T : GestureHandler<T>> updateGestureHandlerHelper(handlerTag: Int, config: ReadableMap) {
-    val handler = registry.getHandler(handlerTag) as T?
-    if (handler != null) {
-      val factory = RNGestureHandlerFactoryUtil.findFactoryForHandler(handler) ?: return
-      interactionManager.dropRelationsForHandlerWithTag(handlerTag)
-      interactionManager.configureInteractions(handler, config)
-      factory.setConfig(handler, config)
-    }
+    val handler = registry.getHandler(handlerTag) as T? ?: return
+    val factory = RNGestureHandlerFactoryUtil.findFactoryForHandler(handler) ?: return
+    interactionManager.dropRelationsForHandlerWithTag(handlerTag)
+    interactionManager.configureInteractions(handler, config)
+    factory.setConfig(handler, config)
   }
 
   @ReactMethod
@@ -161,9 +157,7 @@ class RNGestureHandlerModule(reactContext: ReactApplicationContext?) :
 
   fun registerRootHelper(root: RNGestureHandlerRootHelper) {
     synchronized(roots) {
-      if (root in roots) {
-        throw IllegalStateException("Root helper$root already registered")
-      }
+      assert(root !in roots) { "Root helper$root already registered" }
       roots.add(root)
     }
   }