why I'm getting "fd must not be null" validation error on adding sticker pack to WhatsApp using contentProvider

Question

I'm developing an android application for adding custom stickers to WhatsApp.On adding sticker to WhatsApp a error dailog is shown with message "There is some issue with this sticker pack and it cannot be added to Whatsap". The error I get onActivitResult is "fd should not be invalid". I can't track down the reason for this error.

This is my json file which i create in my project:

[
   {
      "identifier":"2",
      "isWhitelisted":false,
      "licenseAgreementWebsite":"",
      "name":"Prank",
      "privacyPolicyWebsite":"",
      "publisher":"Bilal",
      "publisherEmail":"",
      "publisherWebsite":"",
      "stickers":[
         {
            "emojis":[
               
            ],
            "imageFileName":"0",
            "size":0,
            "uri":"/storage/emulated/0/Android/media/com.firebase.stickersload/Prank/image_0.webp"
         },
         {
            "emojis":[
               
            ],
            "imageFileName":"1",
            "size":0,
            "uri":"/storage/emulated/0/Android/media/com.firebase.stickersload/Prank/image_1.webp"
         },
         {
            "emojis":[
               
            ],
            "imageFileName":"2",
            "size":0,
            "uri":"/storage/emulated/0/Android/media/com.firebase.stickersload/Prank/image_2.webp"
         },
         {
            "emojis":[
               
            ],
            "imageFileName":"3",
            "size":0,
            "uri":"/storage/emulated/0/Android/media/com.firebase.stickersload/Prank/image_3.webp"
         },
         {
            "emojis":[
               
            ],
            "imageFileName":"4",
            "size":0,
            "uri":"/storage/emulated/0/Android/media/com.firebase.stickersload/Prank/image_4.webp"
         }
      ],
      "stickersAddedIndex":5,
      "totalSize":0,
      "trayImageFile":"trayimage",
      "trayImageUri":"/storage/emulated/0/Android/media/com.firebase.stickersload/Prank/image_0.png"
   }
]

Here is my contentProvider Method "openAssetFile" in which this method is occurring.

 override fun openAssetFile(uri: Uri, mode: String): AssetFileDescriptor? {
        val matchCode = MATCHER.match(uri)
        Log.d("de_sticker", uri.toString() + " facffffff")
        Log.w("de_sticker", uri.path + " uri path")
        val pathSegments = uri.pathSegments
        val csp: StickerPack? = StickerBook.getStickerPackByIdWithContext(
            pathSegments[pathSegments.size - 2],
            context
        )
        Log.d("de_sticker", "openAssetFile: id: ${pathSegments.size-2}")

        if (csp != null) {
            val filename = pathSegments[pathSegments.size - 1]
            Log.d("de_sticker", "openAssetFile: path segments file name: ${filename}")
            var pfd: ParcelFileDescriptor? = null

            try {
                if (filename == "trayimage" && csp.trayImageFile != null) {

                    pfd = Objects.requireNonNull(context)!!.contentResolver.openFileDescriptor(
                        csp.trayImageUri!!, "r"
                    )
                    Log.d("de_sticker", "openAssetFile: pdf is:  ${pfd}")
                    Log.d(
                        "de_sticker",
                        java.lang.String.valueOf(csp.trayImageFile) + ""
                    )
                } else {
                    try {
                        pfd = Objects.requireNonNull(context)!!.contentResolver.openFileDescriptor(
                            csp.getStickerById(Integer.valueOf(filename))!!.uri!!, "r"
                        )
                        Log.d("de_sticker", "openAssetFile: else condition $pfd")
                        Log.w(
                            "ASSETFILE ACTUAL URI", java.lang.String.valueOf(
                                csp.getStickerById(
                                    Integer.valueOf(filename)
                                )!!.uri
                            ) + ""
                        )
                    } catch (e: NullPointerException) {
                        Log.d(
                            "de_sticker",
                            "WhatsApp tried to access a non existent sticker, id: $filename"
                        )
                    }
                }
            }
        catch (e: Exception) {
                Log.d("de_sticker", "openAssetFile: ${e.message}")
                e.printStackTrace()
            }
            Log.d("de_sticker", "openAssetFile: pfd is $pfd")
            return AssetFileDescriptor(pfd, 0, AssetFileDescriptor.UNKNOWN_LENGTH)
        }
        return getImageAsset(uri)
        /*if (matchCode == STICKERS_ASSET_CODE || matchCode == STICKER_PACK_TRAY_ICON_CODE) {
            return getImageAsset(uri);
        }
        return null;*/
    }

Is there something i am missing here? Can somebody please help me out with this. Any help will be appreciated. Thank you.

Note: all the given uris(images) are placed in my mobile device and i allow all required permissions as well