title: After Angular 10 update: TypeError: Cannot assign to read only property 'skill_id_array' of object '[object Object]'
body: <p>First, I am not using TypeScript strict mode or NGRX store as referred to often online for such a problem .  My model is in Nestjs / TypeORM /GraphQL on the server, not in Angular, and all I do is bring an object from the db to Angular and I want to replace integers in an array property with strings for presentation in a data table.  This object never goes back to the db for type checking on the server.  This worked fine for a couple of years until I upgraded to Angular 10 and TypeScript 4.</p>
  <p>The offending code is in a loop for each id in the original array and replacing it with a name string from the db.  itemObject is derived from a forEach loop through search results, nothing special.  Each item in membersArray is an object that streams into my code from an Observable.  No manipulations in this process.</p>
  <p><code>membersArray.forEach(itemObject =&gt; {...</code></p>
  <p><code>itemObject.skill_id_array = namesArray.join(', ');</code></p>
  <p>There is no TypeScript readonly on any of the properties in Angular.</p>
  <p>Is there something under the hood that has changed?</p>
  <p>Copying to a new object works but seems like a stupid extra step.</p>
  <p><code>const newObject = { ... itemObject};</code></p>