Minor cleanup

Fixing some things that were errors when compiling against SDK 33.

app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/ReaderPageImageView.kt

@@ -311,7 +311,7 @@ open class ReaderPageImageView @JvmOverloads constructor(
                             return true
                         }
 
-                        override fun onSingleTapConfirmed(e: MotionEvent?): Boolean {
+                        override fun onSingleTapConfirmed(e: MotionEvent): Boolean {
                             this@ReaderPageImageView.onViewClicked()
                             return super.onSingleTapConfirmed(e)
                         }

app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonFrame.kt

@@ -44,7 +44,7 @@ class WebtoonFrame(context: Context) : FrameLayout(context) {
      * Scale listener used to delegate events to the recycler view.
      */
     inner class ScaleListener : ScaleGestureDetector.SimpleOnScaleGestureListener() {
-        override fun onScaleBegin(detector: ScaleGestureDetector?): Boolean {
+        override fun onScaleBegin(detector: ScaleGestureDetector): Boolean {
             recycler?.onScaleBegin()
             return true
         }
@@ -63,13 +63,13 @@ class WebtoonFrame(context: Context) : FrameLayout(context) {
      * Fling listener used to delegate events to the recycler view.
      */
     inner class FlingListener : GestureDetector.SimpleOnGestureListener() {
-        override fun onDown(e: MotionEvent?): Boolean {
+        override fun onDown(e: MotionEvent): Boolean {
             return true
         }
 
         override fun onFling(
-            e1: MotionEvent?,
-            e2: MotionEvent?,
+            e1: MotionEvent,
+            e2: MotionEvent,
             velocityX: Float,
             velocityY: Float,
         ): Boolean {