fix eslint errors

Author: a-tarasyuk

src/compiler/checker.ts

@@ -21602,7 +21602,7 @@ namespace ts {
             checkMode: CheckMode,
             reportErrors: boolean,
             containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined,
-        ): ReadonlyArray<Diagnostic> | undefined {
+        ): readonly Diagnostic[] | undefined {
 
             const errorOutputContainer: { errors?: Diagnostic[], skipLogging?: boolean } = { errors: undefined, skipLogging: true };
             if (isJsxOpeningLikeElement(node)) {