Fix crash opening File > Export if it previously was set to the bounds of a now-deleted artboard (#3577)

fix : Crash loading export dialogue

editor/src/messages/dialog/dialog_message_handler.rs

@@ -1,6 +1,7 @@
 use super::simple_dialogs::{self, AboutGraphiteDialog, DemoArtworkDialog, LicensesDialog};
 use crate::application::GRAPHITE_GIT_COMMIT_DATE;
 use crate::messages::dialog::simple_dialogs::LicensesThirdPartyDialog;
+use crate::messages::frontend::utility_types::ExportBounds;
 use crate::messages::layout::utility_types::widget_prelude::*;
 use crate::messages::prelude::*;
 
@@ -85,6 +86,13 @@ impl MessageHandler<DialogMessage, DialogMessageContext<'_>> for DialogMessageHa
 						.collect();
 
 					self.export_dialog.artboards = artboards;
+
+					if let ExportBounds::Artboard(layer) = self.export_dialog.bounds {
+						if !self.export_dialog.artboards.contains_key(&layer) {
+							self.export_dialog.bounds = ExportBounds::AllArtwork;
+						}
+					}
+
 					self.export_dialog.has_selection = document.network_interface.selected_nodes().selected_layers(document.metadata()).next().is_some();
 					self.export_dialog.send_dialog_to_frontend(responses);
 				}

editor/src/messages/dialog/export_dialog/export_dialog_message_handler.rs

@@ -130,7 +130,7 @@ impl LayoutHolder for ExportDialogMessageHandler {
 		} else {
 			self.bounds
 		};
-		let index = choices.iter().flatten().position(|(bounds, _, _)| *bounds == current_bounds).unwrap();
+		let index = choices.iter().flatten().position(|(bounds, _, _)| *bounds == current_bounds).unwrap_or(0);
 
 		let mut entries = choices
 			.into_iter()