When I create the apk on release mode it crashes on start up 

The problem happens when I enable minifyEnabled for proguard and I solved it by adding below code to proguard-rules.pro

```
-keep class my.package.name.** {*;}

```

I think the reason is proguard delete some of my code but I don't know which part because it obscure my code and reading logcat is useless . 
Is there anyway I understand the logcat message ? 

```
java.lang.NullPointerException: throw with null exception
    at e.a.z.a(:176)
    at i.n.run(:71)

```