Fixed number fields bug

Added a check to prevent null values from causing issues with number fields.

addons/godot_data_editor/item_manager.gd

@@ -469,12 +469,13 @@ func delete_class(item_class):
 	directory.remove(config_class_directory + "/" + item_class + ".png")
 
 func create_class(name, icon_path):
+	name = sanitize_string(name)
+
 	# Check if the classes folder already exists. If not, create it-
 	var directory = Directory.new()
 	if not directory.dir_exists(config_class_directory):
 		directory.make_dir(config_class_directory)
 	
-	name = sanitize_string(name)
 	if name == "":
 		emit_signal("class_insertion_failed", tr("Invalid name"), tr("The class name cannot be empty."))
 		return 

addons/godot_data_editor/property_item.gd

@@ -130,6 +130,8 @@ func create_bool():
 	control.connect("toggled", self, "property_value_changed", [])
 
 func create_number():
+	if value == null:
+		value = 0
 	if hint == PROPERTY_HINT_RANGE:
 		var control_min = -16777216
 		var control_max = 16777216

demo/addons/godot_data_editor/property_item.gd

@@ -130,6 +130,8 @@ func create_bool():
 	control.connect("toggled", self, "property_value_changed", [])
 
 func create_number():
+	if value == null:
+		value = 0
 	if hint == PROPERTY_HINT_RANGE:
 		var control_min = -16777216
 		var control_max = 16777216