[Bug] <title>Crash when entering non-numeric input in Tabs setting (#NumberFormatException)

[khxmyca]

Describe the bug

While testing the developer settings interface, I encountered a crash caused by entering a non-numeric string in the Tabs configuration screen.

This occurred because the input field accepts full keyboard input (including letters), and when a user accidentally types a non-digit character (e.g., "12w"), the app crashes due to an unhandled NumberFormatException. In typical UX flows, such scenarios would ideally be caught by input validation or result in a friendly user message.

While this feature is in the developer settings, accidental non-numeric input is quite easy when a full keyboard is shown. This can result in unexpected crashes that affect the user experience. Implementing a simple input validation would likely resolve the issue efficiently.

stack trace:
FATAL EXCEPTION: main
Process: com.duckduckgo.mobile.android.debug, PID: 10180
java.lang.NumberFormatException: For input string: "12w"
at java.lang.Integer.parseInt(Integer.java:797)
at java.lang.Integer.parseInt(Integer.java:915)
at com.duckduckgo.app.dev.settings.tabs.DevTabsActivity.onCreate$lambda$0(DevTabsActivity.kt:54)
at com.duckduckgo.app.dev.settings.tabs.DevTabsActivity.$r8$lambda$za8548hGpMFoYBlxbLjq6xdk8Y0(Unknown Source:0)
at com.duckduckgo.app.dev.settings.tabs.DevTabsActivity$$ExternalSyntheticLambda1.onClick(D8$$SyntheticClass:0)
at android.view.View.performClick(View.java:7659)
at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:1218)
at android.view.View.performClickInternal(View.java:7636)
at android.view.View.-$$Nest$mperformClickInternal(Unknown Source:0)
at android.view.View$PerformClick.run(View.java:30156)
at android.os.Handler.handleCallback(Handler.java:958)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loopOnce(Looper.java:205)
at android.os.Looper.loop(Looper.java:294)
at android.app.ActivityThread.main(ActivityThread.java:8177)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:552)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:971)

How to Reproduce

1.Open the DuckDuckGo app
2.Navigate to:Setting → Developer Settings → Tabs
3.In the input field, enter a string containing letters (e.g., 12w)
4.Click the "Add Tabs" button
5.Observe the app crash

test.webm

Expected behavior

The app should gracefully reject or sanitize invalid inputs (e.g., with toIntOrNull() and a fallback), or prompt the user with an error message instead of crashing.

Environment

- DDG App Version:5.227.0
- Device:Pixel 4
- OS:Android 14

[github-actions]

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[anikiki]

Thank you for letting us know! This is just a test screen, so we don’t plan to address this issue at the moment.