fix(41965): fix error in definite assignment assertion context (#41989)

src/compiler/checker.ts

@@ -40134,7 +40134,9 @@ namespace ts {
             if (node.exclamationToken && (node.parent.parent.kind !== SyntaxKind.VariableStatement || !node.type || node.initializer || node.flags & NodeFlags.Ambient)) {
                 const message = node.initializer
                     ? Diagnostics.Declarations_with_initializers_cannot_also_have_definite_assignment_assertions
-                    : Diagnostics.Declarations_with_definite_assignment_assertions_must_also_have_type_annotations;
+                    : !node.type
+                        ? Diagnostics.Declarations_with_definite_assignment_assertions_must_also_have_type_annotations
+                        : Diagnostics.A_definite_assignment_assertion_is_not_permitted_in_this_context;
                 return grammarErrorOnNode(node.exclamationToken, message);
             }