Merge pull request #22073 from Albab-Hasan/fix-22071-empty-block-comment-panic

fix: handle empty `/**/` in block_to_line assist

Author: ChayimFriedman2

crates/ide-assists/src/handlers/convert_comment_block.rs

@@ -381,6 +381,21 @@ fn main() {
         );
     }
 
+    #[test]
+    fn empty_block_to_line() {
+        check_assist(
+            convert_comment_block,
+            r#"
+/**/$0
+fn main() {}
+"#,
+            r#"
+
+fn main() {}
+"#,
+        );
+    }
+
     #[test]
     fn end_of_line_block_to_line() {
         check_assist_not_applicable(

crates/syntax/src/ast/token_ext.rs

@@ -32,11 +32,7 @@ impl ast::Comment {
     }
 
     pub fn prefix(&self) -> &'static str {
-        let &(prefix, _kind) = CommentKind::BY_PREFIX
-            .iter()
-            .find(|&(prefix, kind)| self.kind() == *kind && self.text().starts_with(prefix))
-            .unwrap();
-        prefix
+        self.kind().prefix()
     }
 
     /// Returns the textual content of a doc comment node as a single string with prefix and suffix