When an exception is thrown from within a dart file from an imported package VSCode will automatically open that source file to show where the exception was thrown. Once this fi
You need to enable one or two Dart Code settings:
Dart Code
Add to your user settings the following:
"dart.debugExternalLibraries": true, "dart.debugSdkLibraries": true,
The first will allow debugging of pub packages; while the second will allow debugging of Flutter sdk.