The lower constraint ends up meaning that webdev latest doesn't work with this package.
Webdev latest requires build_runner 1.5.x but if you put that in your pubspec then you get errors like this from pub:
Resolving dependencies...
Because build_runner >=1.3.4 depends on build_config >=0.4.0 <0.4.1 and pageloader >=3.0.0 depends on build_config ^0.3.1, build_runner >=1.3.4 is incompatible with pageloader >=3.0.0.
So, because angular_tour_of_heroes depends on both build_runner ^1.5.0 and pageloader ^3.0.0, version solving failed.
The lower constraint ends up meaning that webdev latest doesn't work with this package.
Webdev latest requires build_runner 1.5.x but if you put that in your pubspec then you get errors like this from pub: