Fix v2021_2 compatibility.

Author: CoreyD97

src/main/java/com/coreyd97/burpcustomizer/BurpCustomizer.java

@@ -43,7 +43,7 @@ public void registerExtenderCallbacks(IBurpExtenderCallbacks callbacks) {
         originalBurpTheme = UIManager.getLookAndFeel();
 
         String sourceEnum = callbacks.loadExtensionSetting("source");
-        if(sourceEnum.equalsIgnoreCase("")){
+        if(sourceEnum == null || sourceEnum.equalsIgnoreCase("")){
             themeSource = ThemeSource.BUILTIN;
         }else {
             themeSource = ThemeSource.valueOf(sourceEnum);
@@ -55,7 +55,7 @@ public void registerExtenderCallbacks(IBurpExtenderCallbacks callbacks) {
         if(previousTheme.isPresent()) selectedBuiltIn = previousTheme.get();
 
         String themeFilePref = callbacks.loadExtensionSetting("themeFile");
-        if(!themeFilePref.equalsIgnoreCase("")){
+        if(themeFilePref != null && !themeFilePref.equalsIgnoreCase("")){
             selectedThemeFile = new File(themeFilePref);
             if(!selectedThemeFile.exists()) selectedThemeFile = null;
         }

src/main/java/com/coreyd97/burpcustomizer/CustomTheme.java

@@ -8,11 +8,12 @@
 
 public class CustomTheme extends IntelliJTheme.ThemeLaf {
 
-    Class burpDark, burpLight;
+    Class burpLaf, burpDark, burpLight;
 
     public CustomTheme(IntelliJTheme.ThemeLaf base) {
         super(base.getTheme());
         try {
+            this.burpLaf = ClassLoader.getSystemClassLoader().loadClass("burp.theme.BurpLaf");
             this.burpDark = ClassLoader.getSystemClassLoader().loadClass("burp.theme.BurpDarkLaf");
             this.burpLight = ClassLoader.getSystemClassLoader().loadClass("burp.theme.BurpLightLaf");
         }catch (Exception e){
@@ -37,12 +38,14 @@ public UIDefaults getDefaults() {
             defaults = super.getDefaults();
             BurpCustomizer.callbacks.printError("Could not get Burp base theme! - " + e.getMessage());
         }
-//        defaults = super.getDefaults(); //Debugging. Uncomment to overwrite all Burp defaults.
-        defaults.putAll(super.getDefaults());
+
+        UIDefaults superDefaults = super.getDefaults();
+        superDefaults.remove("SplitPaneUI"); //Do not remove Burp's UI delegates.
+        superDefaults.remove("TabbedPaneUI");
+        defaults.putAll(superDefaults);
 
         //For some reason, using lazy loading in getAdditionalDefaults for this property causes issues...
         defaults.put("TabbedPane.selectedBackground", defaults.get("TabbedPane.background"));
-
         return defaults;
     }