NullPointerException, getPhone error when trying SKD-21, Messages displaying on Samsung Galaxy s4 after update to Lollipop 5.0.1
The error is being generated by a package named com.woodslink.android.wiredheadphoneroutingfix, which appears to be the package name for SoundAbout. Based on the surrounding context, it looks like there may be a bug in the app that is causing it to misbehave on Android 5.0+, at least in your case. Essentially, the Android upgrade broke SoundAbout.

You could potentially try to downgrade your device if you wanted to, but that would have larger ramifications as well. A better alternative would likely be to simply report the issue to the developer of SoundAbout. You can do this by using the email or contact us feature provided by the developer of the app. I'm sure they'd like to get it fixed, and if you provide the error message it should give them at least a decent start for their debugging. 

Unfortunately, there is not much you can do to fix the error on your own (aside from the aforementioned system downgrade).

Note: SoundAbout is no longer available on Play Store.