parser: simplify COPY STDIN payload guard

Author: LucaCappelletti94

src/parser/mod.rs

@@ -11027,13 +11027,11 @@ impl<'a> Parser<'a> {
         while let Some(opt) = self.maybe_parse(|parser| parser.parse_copy_legacy_option())? {
             legacy_options.push(opt);
         }
-        let values = if let CopyTarget::Stdin = target {
-            if self.peek_token_ref().token == Token::EOF {
-                vec![]
-            } else {
-                self.expect_token(&Token::SemiColon)?;
-                self.parse_tsv()
-            }
+        let values = if matches!(target, CopyTarget::Stdin)
+            && self.peek_token_ref().token != Token::EOF
+        {
+            self.expect_token(&Token::SemiColon)?;
+            self.parse_tsv()
         } else {
             vec![]
         };