fix(shadcn): check for empty css vars (#6733)

* fix(shadcn): check for empty css vars

* chore: changeset

Author: shadcn

.changeset/shaggy-months-tease.md

@@ -0,0 +1,5 @@
+---
+"shadcn": patch
+---
+
+check for empty css vars

packages/shadcn/src/utils/updaters/update-css-vars.ts

@@ -24,7 +24,7 @@ export async function updateCssVars(
     tailwindConfig?: z.infer<typeof registryItemTailwindSchema>["config"]
   }
 ) {
-  if (!config.resolvedPaths.tailwindCss) {
+  if (!config.resolvedPaths.tailwindCss || !Object.keys(cssVars ?? {}).length) {
     return
   }