fix(tag-drop): clear drag highlight before readonly early return

Author: waleedlatif1

apps/sim/app/workspace/[workspaceId]/w/[workflowId]/components/panel/components/editor/components/sub-block/components/variables-input/variables-input.tsx

@@ -338,9 +338,9 @@ export function VariablesInput({
   }
 
   const handleEditorDrop = (e: React.DragEvent, assignmentId: string) => {
-    if (isReadOnly) return
     e.preventDefault()
     setDragHighlight((prev) => ({ ...prev, [assignmentId]: false }))
+    if (isReadOnly) return
     try {
       const data = JSON.parse(e.dataTransfer.getData('application/json'))
       if (data.type !== 'connectionBlock') return