Export screen: stop using toasts for save errors

app/src/main/java/org/fairscan/app/MainActivity.kt

@@ -317,11 +317,6 @@ class MainActivity : ComponentActivity() {
                             exportViewModel.onRequestSave(context)
                         }
                     }
-
-                    is ExportEvent.SaveError -> {
-                        val text = getString(R.string.error_save)
-                        Toast.makeText(context, text, Toast.LENGTH_SHORT).show()
-                    }
                 }
             }
         }

app/src/main/java/org/fairscan/app/ui/screens/export/ExportViewModel.kt

@@ -54,7 +54,6 @@ import kotlin.coroutines.suspendCoroutine
 
 sealed interface ExportEvent {
     data object RequestSave : ExportEvent
-    data object SaveError : ExportEvent
 }
 
 class ExportViewModel(container: AppContainer, val imageRepository: ImageRepository): ViewModel() {
@@ -208,7 +207,9 @@ class ExportViewModel(container: AppContainer, val imageRepository: ImageReposit
                 }
             } catch (e: Exception) {
                 logger.e("FairScan", "Failed to save PDF", e)
-                _events.emit(ExportEvent.SaveError)
+                _uiState.update {
+                    it.copy(errorMessage = context.getString(R.string.error_save))
+                }
             } finally {
                 _uiState.update { it.copy(isSaving = false) }
             }