Signed APK - Null Pointer Exception

Question

My Android App is working fine when unsigned. But after singed in when i am opening my app then it is showing Null Pointer Exception.

I tried to create signed apk by "Android Studio" and by "assembleRelase". But facing same exception in both.

Key store file , credential , alias all things are right. but not able to find out what's the issue?

Getting Following exception with signed apk -

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.SearchView.setSearchableInfo(android.app.SearchableInfo)' on a null object reference
    at com.example.pck.MyActivity.onCreateOptionsMenu(Unknown Source)
    at android.app.Activity.onCreatePanelMenu(Activity.java:2820)
    at android.support.v4.app.FragmentActivity.onCreatePanelMenu(Unknown Source)
    at android.support.v7.internal.view.k.onCreatePanelMenu(Unknown Source)
    at android.support.v7.app.ai.onCreatePanelMenu(Unknown Source)
    at android.support.v7.internal.view.k.onCreatePanelMenu(Unknown Source)
    at android.support.v7.internal.a.d.f(Unknown Source)
    at android.support.v7.internal.a.e.run(Unknown Source)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:135)
    at android.app.ActivityThread.main(ActivityThread.java:5254)
    at java.lang.reflect.Method.invoke(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:898)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693)

and my gradle file is as following -

  android {
compileSdkVersion 21
buildToolsVersion "22.0.1"

defaultConfig {
    applicationId "com.example.app"
    minSdkVersion 17
    targetSdkVersion 22
}

signingConfigs {
    release {
        storeFile file("myfile.keystore")
        storePassword "password"
        keyAlias "alias"
        keyPassword "password"
    }
}

buildTypes {
    release {
        minifyEnabled true
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
        signingConfig signingConfigs.release
    }
}

}

Could anyone please suggest me , what would be the issue?

Thanks in advance!