fix(ngcc): log Angular error codes correctly (#34014)

Replaces the "TS-99" sequence with just "NG", so that error codes are
logged correctly.

PR Close #34014

packages/compiler-cli/src/ngtsc/diagnostics/src/util.ts

@@ -6,10 +6,17 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import * as ts from 'typescript';
-
 const ERROR_CODE_MATCHER = /(\u001b\[\d+m ?)TS-99(\d+: ?\u001b\[\d+m)/g;
 
+/**
+ * During formatting of `ts.Diagnostic`s, the numeric code of each diagnostic is prefixed with the
+ * hard-coded "TS" prefix. For Angular's own error codes, a prefix of "NG" is desirable. To achieve
+ * this, all Angular error codes start with "-99" so that the sequence "TS-99" can be assumed to
+ * correspond with an Angular specific error code. This function replaces those occurrences with
+ * just "NG".
+ *
+ * @param errors The formatted diagnostics
+ */
 export function replaceTsWithNgInErrors(errors: string): string {
   return errors.replace(ERROR_CODE_MATCHER, '$1NG$2');
 }