Viewing all current source code problems
(View > Tool Windows > Dart Analysis).
Any analysis issues are shown in the Dart Analysis pane:

Running and debugging

Note:
  You can debug your app in a few ways.

Using DevTools, a suite of debugging and profiling
tools that run in a browser
and include the Flutter inspector.

Using Android Studio’s (or IntelliJ’s) built-in debugging
features, such as the ability to set breakpoints.

Using the Flutter inspector, directly available in
Android Studio and IntelliJ.

The instructions below describe features available in Android
  Studio and IntelliJ. For information on launching DevTools,
  see Running DevTools from Android Studio in the
  DevTools docs.

Running and debugging are controlled from the main toolbar:

Selecting a target