the application crashes when trying to change the font

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Version: 1.8.1

Crash error: java.lang.RuntimeException: Unable to start activity ComponentInfo{fr.xgouchet.texteditor/fr.xgouchet.texteditor.TedFontActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.util.ArrayList.add(java.lang.Object)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2723) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2784) at android.app.ActivityThread.-wrap12(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1523) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:163) at android.app.ActivityThread.main(ActivityThread.java:6238) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:933) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.util.ArrayList.add(java.lang.Object)' on a null object reference at fr.xgouchet.texteditor.TedFontActivity.onCreate(TedFontActivity.java:29) at android.app.Activity.performCreate(Activity.java:6868) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2676) ... 9 more