fix category delete

src/main/kotlin/space/luminic/budgerapp/services/CategoryService.kt

@@ -3,6 +3,7 @@ package space.luminic.budgerapp.services
 
 import kotlinx.coroutines.reactive.awaitFirstOrNull
 import kotlinx.coroutines.reactive.awaitSingle
+import kotlinx.coroutines.reactor.awaitSingleOrNull
 import org.bson.Document
 import org.bson.types.ObjectId
 import org.slf4j.LoggerFactory
@@ -135,6 +136,7 @@ class CategoryService(
     suspend fun deleteCategory(space: Space, categoryId: String) {
         findCategory(space, categoryId)
         val transactions = financialService.getTransactions(space.id!!, categoryId = categoryId).awaitSingle()
+        if (transactions.isNotEmpty()) {
             val otherCategory = try {
                 findCategory(space, name = "Другое")
             } catch (nfe: NotFoundException) {
@@ -148,10 +150,13 @@ class CategoryService(
                     )
                 ).awaitSingle()
             }
+
+
             transactions.map { transaction ->
                 transaction.category = otherCategory
                 financialService.editTransaction(transaction)
             }
+        }
         val budgets = financialService.findProjectedBudgets(
             ObjectId(space.id),
             projectKeys = arrayOf(
@@ -171,7 +176,7 @@ class CategoryService(
             budget.categories.removeIf { it.category.id == categoryId }
             budgetRepo.save(budget)
         }
-        categoryRepo.deleteById(categoryId).awaitSingle()
+        categoryRepo.deleteById(categoryId).awaitSingleOrNull()
     }
 
 }