Use SyncPromise internally & Remove deprecated API & Trim Public API (#1858)

* ref: Move PromiseBuffer and Error to utils package

* ref: Remove all async api

* ref: Remove invokeClientAsync function

* feat: Finish Node SDK

* feat: SyncPromise implementation

* fix: Browser SDK

* fix: beforeSend callback

* fix: Core tests

* fix: linting and tests

* fix: browser npm package + add error for manual tests

* meta: Remove deprecations

* fix: Typedocs and public exposed functions

* meta: Changelog

* Apply suggestions from code review

Co-Authored-By: HazAT <[email protected]>

* fix: CodeReview

* feat: #1871

Author: HazAT

packages/browser/src/backend.ts

@@ -1,5 +1,6 @@
 import { BaseBackend, Options } from '@sentry/core';
 import { SentryEvent, SentryEventHint, Severity, Transport } from '@sentry/types';
+import { SentryError } from '@sentry/utils/error';
 import { isDOMError, isDOMException, isError, isErrorEvent, isPlainObject } from '@sentry/utils/is';
 import { supportsBeacon, supportsFetch } from '@sentry/utils/supports';
 import { SyncPromise } from '@sentry/utils/syncpromise';