Use correct type

Author: jakebailey

src/compiler/program.ts

@@ -6,8 +6,8 @@ import {
     append,
     arrayFrom,
     arrayIsEqualTo,
-    AsExpression,
     AssertClause,
+    AssertionExpression,
     BuilderProgram,
     CancellationToken,
     canHaveDecorators,
@@ -2931,7 +2931,7 @@ export function createProgram(rootNamesOrOptions: readonly string[] | CreateProg
                         return "skip";
                     case SyntaxKind.AsExpression:
                     case SyntaxKind.TypeAssertionExpression:
-                        diagnostics.push(createDiagnosticForNode((node as AsExpression).type, Diagnostics.Type_assertion_expressions_can_only_be_used_in_TypeScript_files));
+                        diagnostics.push(createDiagnosticForNode((node as AssertionExpression).type, Diagnostics.Type_assertion_expressions_can_only_be_used_in_TypeScript_files));
                         return "skip";
                     case SyntaxKind.SatisfiesExpression:
                         diagnostics.push(createDiagnosticForNode((node as SatisfiesExpression).type, Diagnostics.Type_satisfaction_expressions_can_only_be_used_in_TypeScript_files));