Revert "fix(core): ErrorHandler should not rethrow an error by default (#13534)"

This reverts commit 1aebea52e1.

packages/core/src/error_handler.ts

@@ -41,7 +41,12 @@ export class ErrorHandler {
    */
   _console: Console = console;
 
-  constructor(private rethrowError: boolean = false) {}
+  /**
+   * @internal
+   */
+  rethrowError: boolean;
+
+  constructor(rethrowError: boolean = true) { this.rethrowError = rethrowError; }
 
   handleError(error: any): void {
     this._console.error(`EXCEPTION: ${this._extractMessage(error)}`);
@@ -66,6 +71,8 @@ export class ErrorHandler {
       }
     }
 
+    // We rethrow exceptions, so operations like 'bootstrap' will result in an error
+    // when an error happens. If we do not rethrow, bootstrap will always succeed.
     if (this.rethrowError) throw error;
   }