Do not dereference a nullptr.

src/modules/partition/core/PartitionCoreModule.cpp

@@ -172,6 +172,8 @@ void
 PartitionCoreModule::createPartitionTable( Device* device, PartitionTable::TableType type )
 {
     DeviceInfo* info = infoForDevice( device );
+    if ( info )
+    {
         // Creating a partition table wipes all the disk, so there is no need to
         // keep previous changes
         info->forgetChanges();
@@ -180,6 +182,7 @@ PartitionCoreModule::createPartitionTable( Device* device, PartitionTable::Table
         CreatePartitionTableJob* job = new CreatePartitionTableJob( device, type );
         job->updatePreview();
         info->jobs << Calamares::job_ptr( job );
+    }
 
     refresh();
 }