fix(es/react): Default to empty string when emitting refresh signature (#7514)

**Related issue:**

 - Closes #7471.

Author: Austaras

crates/swc_ecma_transforms_react/src/refresh/hook.rs

@@ -407,9 +407,7 @@ impl<'a> HookCollector<'a> {
             None
         }?;
         let mut key = if let Some(name) = lhs {
-            self.cm
-                .span_to_snippet(name.span())
-                .unwrap_or_else(|_| String::new())
+            self.cm.span_to_snippet(name.span()).unwrap_or_default()
         } else {
             String::new()
         };
@@ -421,7 +419,7 @@ impl<'a> HookCollector<'a> {
                 "({})",
                 self.cm
                     .span_to_snippet(expr.args[0].span())
-                    .unwrap_or_else(|_| String::new())
+                    .unwrap_or_default()
             );
         } else if &name.sym == "useReducer" && expr.args.len() > 1 {
             // useReducer second argument is initial state.
@@ -430,7 +428,7 @@ impl<'a> HookCollector<'a> {
                 "({})",
                 self.cm
                     .span_to_snippet(expr.args[1].span())
-                    .unwrap_or_else(|_| "".to_string())
+                    .unwrap_or_default()
             );
         }
 

crates/swc_ecma_transforms_react/src/refresh/mod.rs

@@ -156,7 +156,7 @@ impl<C: Comments> Refresh<C> {
         let hoc_name = match callee.as_ref() {
             Expr::Ident(fn_name) => fn_name.sym.to_string(),
             // original react implement use `getSource` so we just follow them
-            Expr::Member(member) => self.cm.span_to_snippet(member.span).unwrap(),
+            Expr::Member(member) => self.cm.span_to_snippet(member.span).unwrap_or_default(),
             _ => return Persist::None,
         };
         let reg_str = (