fix a not emitted unmatched angle bracket error

compiler/rustc_parse/src/parser/item.rs

@@ -1486,7 +1486,7 @@ impl<'a> Parser<'a> {
                             // `check_trailing_angle_brackets` already emitted a nicer error
                             // NOTE(eddyb) this was `.cancel()`, but `err`
                             // gets returned, so we can't fully defuse it.
-                            err.downgrade_to_delayed_bug();
+                            err.delay_as_bug();
                         }
                     }
                 }

src/test/ui/parser/recover-field-extra-angle-brackets-in-struct-with-a-field.rs

@@ -0,0 +1,6 @@
+struct TypedArenaChunk {
+    next: Option<String>>
+    //~^ ERROR unmatched angle bracket
+}
+
+fn main() {}

src/test/ui/parser/recover-field-extra-angle-brackets-in-struct-with-a-field.stderr

@@ -0,0 +1,11 @@
+error: unmatched angle bracket
+  --> $DIR/recover-field-extra-angle-brackets-in-struct-with-a-field.rs:2:25
+   |
+LL |       next: Option<String>>
+   |  _________________________^
+LL | |
+LL | | }
+   | |_ help: remove extra angle bracket
+
+error: aborting due to previous error
+