Rollup merge of #82720 - henryboisdequin:fix-79040, r=oli-obk

Fix diagnostic suggests adding type `[type error]`

Fixes #79040

### Unresolved questions:

<del>Why does this change output the diagnostic twice (`src/test/ui/79040.rs`)?</del> Thanks `````@oli-obk`````

compiler/rustc_typeck/src/collect/type_of.rs

@@ -722,11 +722,12 @@ fn infer_placeholder_type(
                 format!("{}: {}", item_ident, ty),
                 Applicability::MachineApplicable,
             )
-            .emit();
+            .emit_unless(ty.references_error());
         }
         None => {
             let mut diag = bad_placeholder_type(tcx, vec![span]);
-            if !matches!(ty.kind(), ty::Error(_)) {
+
+            if !ty.references_error() {
                 diag.span_suggestion(
                     span,
                     "replace `_` with the correct type",
@@ -734,6 +735,7 @@ fn infer_placeholder_type(
                     Applicability::MaybeIncorrect,
                 );
             }
+
             diag.emit();
         }
     }