RxJava - Subscribe doesn't catch exception which cause crash - kotlin

Question

I am trying to subscribe to a SingleSource, I have implemented both onSuccess And onError of subscribe method, here is my code:
disposable.add(repository
.getUser1()
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe({
toast(it)
}, {
toast(it.message ?: "Error")
}))
The Problem is When an exception occur in repository it does't being caught in onError
Here is my repository implementation:
class Repository(private val sp: SharedPreferences) {
// It crashes
fun getUser1(): Single<String> = generateUser(name, "Hello")
// it doesn't crash
fun getUser2(): Single<String> = Single.fromCallable { name }.flatMap { generateUser(it, "Hello") }
private var name: String
get() = sp.getString("user", null) ?: throw NoNameException()
set(value) = sp.edit().putString("user", value).apply()
private fun generateUser(name: String, message: String): Single<String> = Single.just("$message $name")
}
And here is the crash Log:
09-24 10:13:40.930 6934-6934/com.mosius.samplerxtest E/AndroidRuntime:
FATAL EXCEPTION: main
Process: com.mosius.samplerxtest, PID: 6934
java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:503)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:826)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:826) 
Caused by: com.mosius.samplerxtest.NoNameException: No Name Supplied
at com.mosius.samplerxtest.Repository.getName(Repository.kt:17)
at com.mosius.samplerxtest.Repository.getUser1(Repository.kt:10)
at com.mosius.samplerxtest.MainActivity$onCreate$1.onClick(MainActivity.kt:24)
at android.view.View.performClick(View.java:6597)
at android.view.View.performClickInternal(View.java:6574)
at android.view.View.access$3100(View.java:778)
at android.view.View$PerformClick.run(View.java:25881)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6649)
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:826)
What's the different between these two implementation?

Answer 1

In the getUser1() method, SingleSource has not been created yet, so it is out of Rx control to handle the exception.
In the Second one the name is being fetched in Rx scope therefore it could handle the exception