Prevent empty difficulty strings from accidentally existing (#832)

* Prevent empty difficulty strings from being inputted

* Also taking into account variants + making separator only show up when both difficulty and variant options are available

Author: Jurtaa

source/funkin/editors/charter/CharterSelection.hx

@@ -40,21 +40,21 @@ class CharterSelectionScreen extends EditorTreeMenuScreen {
 		var screen = new EditorTreeMenuScreen((first || !isVariant) ? (s.name + (isVariant ? ' (${s.variant})' : '')) : s.variant, getID('selectDifficulty'));
 
 		for (d in s.difficulties) if (d != '') screen.add(makeChartOption(d, isVariant ? s.variant : null, s.name));
-		screen.add(new Separator());
+		if (s.difficulties.length > 0 && s.variants.length > 0) screen.add(new Separator()); // Create a separator only when there are both difficulty and variant options available.
 		for (v in s.variants) if (s.metas.get(v) != null) screen.add(makeVariationOption(s.metas.get(v)));
 
 		#if sys
 		screen.insert(0, new NewOption(getID('newDifficulty'), getID('newDifficultyDesc'), () -> {
 			parent.openSubState(new ChartCreationScreen(saveChart));
 		}));
 
-		if (!first) screen.curSelected = 1;
+		if (!first) screen.curSelected = (s.difficulties.length + s.variants.length) > 0 ? 1 : 0;
 		else {
 			cast(screen.members[0], NewOption).itemHeight = 120;
 			screen.insert(1, new NewOption(getID('newVariation'), getID('newVariationDesc'), () -> {
 				parent.openSubState(new VariationCreationScreen(s, saveSong));
 			}));
-			screen.curSelected = 2;
+			screen.curSelected = (s.difficulties.length + s.variants.length) > 0 ? 2 : 1;
 		}
 		#end
 

source/funkin/editors/charter/SongCreationScreen.hx

@@ -435,7 +435,7 @@ class SongCreationScreen extends UISubstateWindow {
 				color: colorWheel.curColor,
 				opponentModeAllowed: opponentModeCheckbox.checked,
 				coopAllowed: coopAllowedCheckbox.checked,
-				difficulties: [for (diff in difficultiesTextBox.label.text.split(",")) diff.trim()]
+				difficulties: [for (diff in difficultiesTextBox.label.text.split(",")) if (diff.length > 0) diff.trim()]
 			});
 
 			if (onSave != null) onSave({