We have had the same problem with angular (7/8).

[dhaneshawate]

We have had the same problem with angular (7/8).
We ended up with a fork where we added the same core-js polyfills that angular does to avoid the zone.js conflict.

FreeDraw.js:

delete:
import 'core-js';

add:
import 'core-js/es6/symbol';
import 'core-js/es6/object';
import 'core-js/es6/function';
import 'core-js/es6/parse-int';
import 'core-js/es6/parse-float';
import 'core-js/es6/number';
import 'core-js/es6/math';
import 'core-js/es6/string';
import 'core-js/es6/date';
import 'core-js/es6/array';
import 'core-js/es6/regexp';
import 'core-js/es6/map';
import 'core-js/es6/weak-map';
import 'core-js/es6/set';

Originally posted by @AndreasOlausson in #141 (comment)

[dhaneshawate]

i have added above code but still the issue remains.
please guide according i am trying to do this in angular 9

[AndreasOlausson]

Try to import Freedraw just before you import Zone.

polyfill.ts (something like this):

import "leaflet-freedraw"
/***************************************************************************************************

• Zone JS is required by Angular itself.
  */
  import 'zone.js/dist/zone'; // Included with Angular CLI.

However, we don't use freedraw any longer, due the lack of "donut-polygon" support so we have written our own "freedraw".

[chriswilley]

In my case, updating zone.js to 0.10.3 solved this issue.

angular/angular#31724 (comment)