Method not found: 'guard'. return internals.guard(

i am new to flutter.when i run this code on flutter web this error occurs.
.pub-cache/hosted/pub.dartlang.org/cloud_firestore_web-1.0.7/lib/src/internals.dart:10:20:

some one help to get rid of the problem

>Solution :

If you updated your flutter sdk to Beta channel, Downgrade your flutter sdk to Stable Channel. Current stable version is 2.10.3

Flutter downgrade command

flutter downgrade v2.10.3

and than

Downgrade flutter to version 2.10.3
? [y|n]:
Type y for Yes to confirm changes