Fix crash caused by freezing Moment.js Locale objects in deepFreeze (#223133)

src/platform/packages/shared/kbn-std/src/deep_freeze.ts

@@ -8,6 +8,7 @@
  */
 
 import type { RecursiveReadonly } from '@kbn/utility-types';
+import moment from 'moment-timezone';
 
 /** @public */
 export type Freezable = { [k: string]: any } | any[];
@@ -23,8 +24,16 @@ export function deepFreeze<T extends Freezable>(object: T) {
   // recursively frozen as well
   for (const value of Object.values(object)) {
     if (value !== null && typeof value === 'object') {
+      if (isMomentLocale(value)) {
+        // Skip moment.Locale instances, moment should not be frozen
+        continue;
+      }
       deepFreeze(value);
     }
   }
   return Object.freeze(object) as RecursiveReadonly<T>;
 }
+
+function isMomentLocale(obj: unknown): obj is moment.Locale {
+  return obj !== null && typeof obj === 'object' && '_longDateFormat' in obj;
+}