Add null check for content provider client in JtxSyncManagerTest

Author: rfc2822

app/src/androidTest/kotlin/at/bitfire/davdroid/sync/JtxSyncManagerTest.kt

@@ -24,6 +24,7 @@ import dagger.hilt.android.testing.HiltAndroidTest
 import okhttp3.HttpUrl.Companion.toHttpUrl
 import org.junit.After
 import org.junit.Assert.assertEquals
+import org.junit.Assume.assumeNotNull
 import org.junit.Assume.assumeTrue
 import org.junit.Before
 import org.junit.Rule
@@ -75,7 +76,9 @@ class JtxSyncManagerTest {
         assumeTrue(PermissionUtils.havePermissions(context, TaskProvider.PERMISSIONS_JTX))
 
         // Acquire the jtx content provider
-        provider = context.contentResolver.acquireContentProviderClient(JtxContract.AUTHORITY)!!
+        val providerOrNull = context.contentResolver.acquireContentProviderClient(JtxContract.AUTHORITY)!!
+        assumeNotNull(providerOrNull)
+        provider = providerOrNull
 
         // Create dummy dependencies
         val service = Service(0, account.name, Service.TYPE_CALDAV, null)