If "Save & Exit" is pressed while quitting, don't close the software …

…if the project failed to save (#920)

* Dont quit if project failed to save

* Formatting

* spell Formatting

src/Autoload/OpenSave.gd

@@ -208,7 +208,7 @@ func open_pxo_file(path: String, untitled_backup := false, replace_empty := true
 
 func save_pxo_file(
 	path: String, autosave: bool, use_zstd := true, project := Global.current_project
-) -> void:
+) -> bool:
 	if !autosave:
 		project.name = path.get_file()
 	var serialized_data := project.serialize()
@@ -218,15 +218,15 @@ func save_pxo_file(
 		)
 		Global.error_dialog.popup_centered()
 		Global.dialog_open(true)
-		return
+		return false
 	var to_save := JSON.stringify(serialized_data)
 	if !to_save:
 		Global.error_dialog.set_text(
 			tr("File failed to save. Converting dictionary to JSON failed.")
 		)
 		Global.error_dialog.popup_centered()
 		Global.dialog_open(true)
-		return
+		return false
 
 	# Check if a file with the same name exists. If it does, rename the new file temporarily.
 	# Needed in case of a crash, so that the old file won't be replaced with an empty one.
@@ -244,14 +244,15 @@ func save_pxo_file(
 	var err := FileAccess.get_open_error()
 	if err != OK:
 		if temp_path.is_valid_filename():
-			return
+			return false
 		Global.error_dialog.set_text(
 			tr("File failed to save. Error code %s (%s)") % [err, error_string(err)]
 		)
 		Global.error_dialog.popup_centered()
 		Global.dialog_open(true)
-		file.close()
-		return
+		if file:  # this would be null if we attempt to save filenames such as "//\\||.pxo"
+			file.close()
+		return false
 
 	if !autosave:
 		current_save_paths[Global.current_project_index] = path
@@ -302,6 +303,7 @@ func save_pxo_file(
 		)
 
 	save_project_to_recent_list(path)
+	return true
 
 
 func open_image_as_new_tab(path: String, image: Image) -> void:

src/Main.gd

@@ -284,12 +284,13 @@ func save_project(path: String) -> void:
 	var zstd: bool = (
 		Global.save_sprites_dialog.get_vbox().get_node("ZSTDCompression").button_pressed
 	)
-	OpenSave.save_pxo_file(path, false, zstd)
-	Global.open_sprites_dialog.current_dir = path.get_base_dir()
-	Global.config_cache.set_value("data", "current_dir", path.get_base_dir())
+	var success = OpenSave.save_pxo_file(path, false, zstd)
+	if success:
+		Global.open_sprites_dialog.current_dir = path.get_base_dir()
+		Global.config_cache.set_value("data", "current_dir", path.get_base_dir())
 
-	if is_quitting_on_save:
-		_quit()
+		if is_quitting_on_save:
+			_quit()
 
 
 func _on_SaveSpriteHTML5_confirmed() -> void: