Eagerly return ExprKind::Err on yield/await in wrong coroutine context

Author: compiler-errors

Diff for: compiler/rustc_ast_lowering/src/expr.rs

@@ -778,10 +778,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
         match self.coroutine_kind {
             Some(hir::CoroutineKind::Async(_)) => {}
             Some(hir::CoroutineKind::Coroutine) | Some(hir::CoroutineKind::Gen(_)) | None => {
-                self.tcx.sess.emit_err(AwaitOnlyInAsyncFnAndBlocks {
+                return hir::ExprKind::Err(self.tcx.sess.emit_err(AwaitOnlyInAsyncFnAndBlocks {
                     await_kw_span,
                     item_span: self.current_item,
-                });
+                }));
             }
         }
         let span = self.mark_span_with_reason(DesugaringKind::Await, await_kw_span, None);
@@ -1500,7 +1500,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         match self.coroutine_kind {
             Some(hir::CoroutineKind::Gen(_)) => {}
             Some(hir::CoroutineKind::Async(_)) => {
-                self.tcx.sess.emit_err(AsyncCoroutinesNotSupported { span });
+                return hir::ExprKind::Err(self.tcx.sess.emit_err(AsyncCoroutinesNotSupported { span }));
             }
             Some(hir::CoroutineKind::Coroutine) | None => {
                 if !self.tcx.features().coroutines {

Diff for: tests/ui/async-await/issue-70594.rs

@@ -3,9 +3,6 @@
 async fn fun() {
     [1; ().await];
     //~^ error: `await` is only allowed inside `async` functions and blocks
-    //~| error: `.await` is not allowed in a `const`
-    //~| error: `.await` is not allowed in a `const`
-    //~| error: `()` is not a future
 }
 
 fn main() {}

Diff for: tests/ui/async-await/issues/issue-62009-1.rs

@@ -11,5 +11,4 @@ fn main() {
     //~^ ERROR `await` is only allowed inside `async` functions and blocks
     (|_| 2333).await;
     //~^ ERROR `await` is only allowed inside `async` functions and blocks
-    //~| ERROR is not a future
 }