Basic Android launcher splash screen

I'm new to writing code and apologize for what I am guessing is probably a very simple question. I followed Android's Build your first app guide. Next, I'm trying to add a launcher splash screen by following a number of tutorials (this being one of them). When I run the app in the emulator it loads so fast that I can't tell if the splash screen works. Is there a way to temporarily slow down the emulator to check the splash screen? Also the app crashes when the Send button is clicked which doesn't make sense because the sendMessage function exists in the MainActivity.

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.myfirstapp, PID: 9242
    java.lang.IllegalStateException: Could not find method sendMessage(View) in a parent or ancestor Context for android:onClick attribute defined on view class androidx.appcompat.widget.AppCompatButton with id 'button'
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.resolveMethod(AppCompatViewInflater.java:436)
        at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:393)
        at android.view.View.performClick(View.java:7125)
        at android.view.View.performClickInternal(View.java:7102)
        at android.view.View.access$3500(View.java:801)
        at android.view.View$PerformClick.run(View.java:27336)
        at android.os.Handler.handleCallback(Handler.java:883)
        at android.os.Handler.dispatchMessage(Handler.java:100)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

I'm honestly not sure what is wrong or if the app is just so small that a splash screen won't show. I'm also not sure the best way to share my project here. So below is all of the code.

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myfirstapp">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">

        <activity android:name=".SplashActivity"
            android:theme="@style/SplashTheme">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity android:name=".DisplayMessageActivity"
                  android:parentActivityName=".MainActivity">
            <!-- For API 15 -->
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value=".MainActivity" />
        </activity>
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />
            </intent-filter>
        </activity>
    </application>
</manifest>

MainActivity.kt

package com.example.myfirstapp

import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.EditText

const val EXTRA_MESSAGE = "come.example.myfirstapp.MESSAGE"

class MainActivity : AppCompatActivity()
{
    override fun onCreate(savedInstanceState: Bundle?)
    {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }

    //Called when user taps Send button
    fun sendMessage(view: View)
    {
        val editText = findViewById<EditText>(R.id.editTextTextPersonName)
        val message = editText.text.toString()
        val intent = Intent(this, DisplayMessageActivity::class.java).apply {putExtra(EXTRA_MESSAGE, message)}
        startActivity(intent)
    }
}

DisplayMessageActivity

package com.example.myfirstapp

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.TextView

class DisplayMessageActivity : AppCompatActivity()
{
    override fun onCreate(savedInstanceState: Bundle?)
    {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_display_message)

        //Get the Intent that started this activity and extract the string
        val message = intent.getStringExtra(EXTRA_MESSAGE)

        //Capture the layout's TextView and set the string as its text
        val text = findViewById<TextView>(R.id.textView).apply {text = message}
    }
}

SplashActivity

package com.example.myfirstapp

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity

class SplashActivity : AppCompatActivity()
{
    override fun onCreate(savedIntanceState: Bundle?)
    {
        setTheme(R.style.AppTheme)
        super.onCreate(savedIntanceState)
        setContentView(R.layout.activity_main)
    }
}

drawable splash_background.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android"
    android:opacity="opaque">
    <item android:drawable="@color/colorPrimary" />
    <item>
        <bitmap android:gravity="center" android:src="@mipmap/ic_launcher" />
    </item>
</layer-list>

values styles.xml

<resources>
    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>

    <!-- Splash Screen theme. -->
    <style name="SplashTheme" parent="Theme.AppCompat.NoActionBar">
        <item name="android:windowBackground">@drawable/splash_background</item>
    </style>
</resources>

Sorry for the novice question, and I hope I'm not breaking any rules by posting it, but would appreciate some guidance. Thanks!

Edit - updated error after help from S T