print <empty> for empty task call stack

Author: branchseer

crates/vite_task_plan/src/context.rs

@@ -66,6 +66,10 @@ pub struct TaskCallStackDisplay {
 
 impl Display for TaskCallStackDisplay {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        if self.frames.is_empty() {
+            write!(f, "<empty>")?;
+            return Ok(());
+        }
         for (i, frame) in self.frames.iter().enumerate() {
             if i > 0 {
                 write!(f, " -> ")?;