diff --git a/distribution/openrct2.d.ts b/distribution/openrct2.d.ts
index 0c2abd31a2..5dc75f276b 100644
--- a/distribution/openrct2.d.ts
+++ b/distribution/openrct2.d.ts
@@ -1881,9 +1881,9 @@ declare global {
          * By default, text buttons have borders and image buttons do not but it can be overridden.
          */
         border?: boolean;
-        image: number;
-        isPressed: boolean;
-        text: string;
+        image?: number;
+        isPressed?: boolean;
+        text?: string;
         onClick: () => void;
     }
 
@@ -1946,8 +1946,8 @@ declare global {
         readonly highlightedCell?: RowColumn;
         canSelect?: boolean;
 
-        onHighlight: (item: number, column: number) => void;
-        onClick: (item: number, column: number) => void;
+        onHighlight?: (item: number, column: number) => void;
+        onClick?: (item: number, column: number) => void;
     }
 
     interface SpinnerWidget extends Widget {
diff --git a/src/openrct2-ui/scripting/CustomListView.cpp b/src/openrct2-ui/scripting/CustomListView.cpp
index 40605cb418..06bf610779 100644
--- a/src/openrct2-ui/scripting/CustomListView.cpp
+++ b/src/openrct2-ui/scripting/CustomListView.cpp
@@ -497,7 +497,7 @@ void CustomListView::MouseDown(const ScreenCoordsXY& pos)
     auto hitResult = GetItemIndexAt(pos);
     if (hitResult)
     {
-        if (hitResult->Row != HEADER_ROW && OnClick.context() != nullptr && OnClick.is_function())
+        if (hitResult->Row != HEADER_ROW)
         {
             if (CanSelect)
             {
@@ -506,12 +506,15 @@ void CustomListView::MouseDown(const ScreenCoordsXY& pos)
             }
 
             auto ctx = OnClick.context();
-            duk_push_int(ctx, static_cast<int32_t>(hitResult->Row));
-            auto dukRow = DukValue::take_from_stack(ctx, -1);
-            duk_push_int(ctx, static_cast<int32_t>(hitResult->Column));
-            auto dukColumn = DukValue::take_from_stack(ctx, -1);
-            auto& scriptEngine = GetContext()->GetScriptEngine();
-            scriptEngine.ExecutePluginCall(Owner, OnClick, { dukRow, dukColumn }, false);
+            if (ctx != nullptr && OnClick.is_function())
+            {
+                duk_push_int(ctx, static_cast<int32_t>(hitResult->Row));
+                auto dukRow = DukValue::take_from_stack(ctx, -1);
+                duk_push_int(ctx, static_cast<int32_t>(hitResult->Column));
+                auto dukColumn = DukValue::take_from_stack(ctx, -1);
+                auto& scriptEngine = GetContext()->GetScriptEngine();
+                scriptEngine.ExecutePluginCall(Owner, OnClick, { dukRow, dukColumn }, false);
+            }
         }
     }
     if (hitResult && hitResult->Row == HEADER_ROW)
@@ -597,11 +600,14 @@ void CustomListView::Paint(rct_window* w, rct_drawpixelinfo* dpi, const rct_scro
                 // Columns
                 if (Columns.size() == 0)
                 {
-                    const auto& text = item.Cells[0];
-                    if (!text.empty())
+                    if (item.Cells.size() != 0)
                     {
-                        ScreenSize cellSize = { std::numeric_limits<int32_t>::max(), LIST_ROW_HEIGHT };
-                        PaintCell(dpi, { 0, y }, cellSize, text.c_str(), isHighlighted);
+                        const auto& text = item.Cells[0];
+                        if (!text.empty())
+                        {
+                            ScreenSize cellSize = { std::numeric_limits<int32_t>::max(), LIST_ROW_HEIGHT };
+                            PaintCell(dpi, { 0, y }, cellSize, text.c_str(), isHighlighted);
+                        }
                     }
                 }
                 else
diff --git a/src/openrct2-ui/scripting/CustomWindow.cpp b/src/openrct2-ui/scripting/CustomWindow.cpp
index b267545e30..1e12909f3a 100644
--- a/src/openrct2-ui/scripting/CustomWindow.cpp
+++ b/src/openrct2-ui/scripting/CustomWindow.cpp
@@ -164,12 +164,15 @@ namespace OpenRCT2::Ui::Windows
             }
             else if (result.Type == "dropdown")
             {
-                auto dukItems = desc["items"].as_array();
-                for (const auto& dukItem : dukItems)
+                if (desc["items"].is_array())
                 {
-                    result.Items.push_back(ProcessString(dukItem));
+                    auto dukItems = desc["items"].as_array();
+                    for (const auto& dukItem : dukItems)
+                    {
+                        result.Items.push_back(ProcessString(dukItem));
+                    }
                 }
-                result.SelectedIndex = desc["selectedIndex"].as_int();
+                result.SelectedIndex = AsOrDefault(desc["selectedIndex"], 0);
                 result.OnChange = desc["onChange"];
             }
             else if (result.Type == "groupbox" || result.Type == "label")