fix buggy isApng()

apng_library/src/main/java/oupson/apng/Utils.kt

@@ -18,6 +18,7 @@ class Utils {
          * @return True if is an APNG
          */
         fun isApng(byteArray: ByteArray) : Boolean {
+            try {
                 val acTL = byteArrayOf(0x66, 0x63, 0x54, 0x4c)
                 loop@ for (i in 0 until byteArray.size) {
                     val it = byteArray.copyOfRange(i, i + 4)
@@ -27,6 +28,9 @@ class Utils {
                     }
                 }
                 return false
+            } catch (e : Exception) {
+                return false
+            }
         }
 
         /**