feat: enhance connection validation and node creation logic, improve type handling in various components

frontend/src/components/nodes/FunctionNode.tsx

@@ -131,7 +131,7 @@ function FunctionNodeComponent({ id, data, width, height, selected }: Props) {
                         }
                     />
                 </div>
-                <div ref={editorContainerRef} className="min-h-0 flex-1 w-full nodrag nopan overflow-hidden border-t border-input">
+                <div ref={editorContainerRef as React.RefObject<HTMLDivElement>} className="min-h-0 flex-1 w-full nodrag nopan overflow-hidden border-t border-input">
                     <CodeMirror
                         // @ts-expect-error ref is { view, state, editor }; package ref type not in our node_modules
                         ref={editorRef}