I'm on the dev channel. I can't run my web app.

This worked previously.

Launching lib/main.dart on Chrome in debug mode...
lib/main.dart:1
../../../.pub-cache/hosted/pub.dartlang.org/url_launcher_web-0.1.4+1/lib/url_launcher_web.dart:22:7: Error: The non-abstract class 'UrlLauncherPlugin' is missing implementations for these members:

• UrlLauncherPlatform.linkDelegate
  Try to either
• provide an implementation,
• inherit an implementation from a superclass or mixin,
• mark the class as abstract, or
• provide a 'noSuchMethod' implementation.

class UrlLauncherPlugin extends UrlLauncherPlatform {
^^^^^^^^^^^^^^^^^
../../../.pub-cache/hosted/pub.dartlang.org/url_launcher_platform_interface-1.0.9/lib/url_launcher_platform_interface.dart:43:20: Context: 'UrlLauncherPlatform.linkDelegate' is defined here.
LinkDelegate get linkDelegate;
^^^^^^^^^^^^
Failed to compile application.