Error when compiling - Kotlin language related

[d-apps]

When I try to run the project I have this error:

e: C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\flutter_pdf_viewer-0.6.1\android\src\main\kotlin\com\pycampers\flutterpdfviewer\PdfActivityThread.kt: (82, 47): The spread operator (*foo) may not be applied to an argument of nullable type

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':flutter_pdf_viewer:compileDebugKotlin'.
> Compilation error. See log for more details

The error is on: configurator = configurator.pages(*opts.getIntArray("pages"))

I already tried to remove the "*" but it gives me another error:

Type mismatch: inferred type is IntArray? but Int was expected

PdfActivityThread.kt

package com.pycampers.flutterpdfviewer

import android.os.Bundle
import android.util.Log
import android.view.View
import com.github.barteksc.pdfviewer.PDFView
import com.github.barteksc.pdfviewer.scroll.DefaultScrollHandle
import java.io.File

// This thread is used to do heavy tasks, like loading the PDF from disk, decrypting it etc.
class PdfActivityThread(
    val activity: PdfActivity,
    val opts: Bundle,
    val pdfView: PDFView,
    val playerController: PlayerController,
    val scrollHandle: DefaultScrollHandle,
    val initialPage: Int
) : Thread() {
    val mode = opts.getString("mode")!!
    val xorDecryptKey: String? = opts.getString("xorDecryptKey")

    fun buildConfigurator(): PDFView.Configurator? {
        val src = opts.getString("src")!!

        xorDecryptKey?.let {
            val bytes = when (mode) {
                "fromFile" -> {
                    Log.d(TAG, "loading encrypted pdf from file { $src }...")
                    readBytesFromFile(src)
                }
                "fromBytes" -> {
                    Log.d(TAG, "loading encrypted pdf from bytes...")
                    readBytesFromSocket(src)
                }
                "fromAsset" -> {
                    Log.d(TAG, "loading encrypted pdf from assets { $src }...")
                    readBytesFromAsset(activity.applicationContext, src)
                }
                else -> throw IllegalArgumentException("invalid mode: $mode.")
            }
            xorEncryptDecrypt(bytes, it)
            return pdfView.fromBytes(bytes)
        }

        return when (mode) {
            "fromFile" -> {
                Log.d(TAG, "loading pdf from file { $src }...")
                pdfView.fromFile(File(src))
            }
            "fromBytes" -> {
                Log.d(TAG, "loading pdf from bytes...")
                pdfView.fromBytes(readBytesFromSocket(src))
            }
            "fromAsset" -> {
                Log.d(TAG, "loading pdf from assets { $src }...")
                pdfView.fromAsset(src)
            }
            else -> throw IllegalArgumentException("invalid mode: $mode.")
        }
    }

    override fun run() {
        pdfView.visibility = View.VISIBLE
        var configurator = buildConfigurator()!!

        configurator = configurator
            .password(opts.getString("password"))
            .nightMode(opts.getBoolean("nightMode"))
            .enableSwipe(opts.getBoolean("enableSwipe"))
            .swipeHorizontal(opts.getBoolean("swipeHorizontal"))
            .autoSpacing(opts.getBoolean("autoSpacing"))
            .pageFling(opts.getBoolean("pageFling"))
            .pageSnap(opts.getBoolean("pageSnap"))
            .onError(activity)
            .onRender(activity)
            .scrollHandle(scrollHandle)
            .onPageChange(playerController)
            .onTap(playerController)
            .defaultPage(initialPage)

        if (opts.containsKey("pages")) {
            configurator = configurator.pages(*opts.getIntArray("pages"))
        }

        configurator.load()
    }
}