build_runner_core-9.3.0 seems to have "import 'dart:mirrors'" which is not supported in Dart runtime
dev_dependencies
I have build_runner: 2.4.15, which is internally dependent on build_runner_core-9.3.0, which shows having import 'dart: mirrors', which is blocking the run app.
build_runner should not be compiled into your app--it is not a runtime dependency.
It should work to move build_runner and anything related from dependencies to dev_dependencies.
@davidmorgan build_runner is included only under dev_dependencies, but when I run the app, it fails. While investigating, I queried for dart:mirrors and noticed that build_runner also appeared in the results. I’m not sure if this is the root cause, but wanted to check with you for clarity.
I guess not, unless you have some package in dependencies that transitively pulls in build_runner.
You can try removing build_runner from your dev dependencies then flutter pub get and try again; you can check the resulting pubspec.lock file to be sure you don't have a transitive dependency on build_runner via some other package.