Fix npe caused by required project in the PaymentStatusView

[Fabtron]

What's new?

Fixed crash of the checkout activity caused of an npe in the payment status view if the user opens the app and is not checked in anymore.

APPS-1261

How to test?

• Apply this patch on the main branch :

index c9d00d905..3dcd483e3 100644
--- a/ui/src/main/java/io/snabble/sdk/ui/checkout/PaymentStatusFragment.kt
+++ b/ui/src/main/java/io/snabble/sdk/ui/checkout/PaymentStatusFragment.kt
@@ -1,6 +1,20 @@
 package io.snabble.sdk.ui.checkout
 
+import android.os.Bundle
+import androidx.lifecycle.lifecycleScope
+import io.snabble.sdk.Snabble
 import io.snabble.sdk.ui.BaseFragment
 import io.snabble.sdk.ui.R
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
 
-open class PaymentStatusFragment : BaseFragment(R.layout.snabble_fragment_payment_status)
\ No newline at end of file
+open class PaymentStatusFragment : BaseFragment(R.layout.snabble_fragment_payment_status){
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        lifecycleScope.launch {
+            delay(4000)
+            Snabble.checkedInProject.value = null
+        }
+    }
+}

• Buy something -> after 4 sec the checkout should crash (see logs)
• Apply the same patch on this branch :

Now the logs should show the following log :
2023-12-18 08:33:57.843 11885-11885 (CheckoutA....java:135) io.snabble.sdk.sample E Project not set

Definition of Done

• Changelog gepflegt
• Dokumentation gepflegt
• Alle Anforderung des Issues sind erfüllt
• Selbst greviewed (aka Self-Reviews (eng))

[cmaier]

Cannot reproduce the bug w/ this patch. What am I doing wrong?