<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.lukekorth.mailable_log">

    <application>
        <provider
            android:name="android.support.v4.content.FileProvider"
            android:authorities="com.lukekorth.mailable_log.fileprovider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/file_paths" />
        </provider>
    </application>

</manifest>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.lukekorth.mailable_log">

    <application>
        <provider
            android:name="android.support.v4.content.FileProvider"
            android:authorities="${applicationId}.fileprovider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/file_paths" />
        </provider>
    </application>

</manifest>

Change provider authority to applicationId
Change provider authority to applicationId
