* Update update_icons.dart

* formatting

* more formatting

* simplify safety checks

* add safety checks tests

* formatting

* update copyright

* naming

* revert copyright

* add `fontFamily` option

* tweak diff messages

* Update update_icons.dart

* don't exit if platform adaptive icon not found

* remove trailing spaces

* remove warning and fix insert_chart (outlined) dartdoc

* x

* add error message when exiting due to failed safety checkes

* fix icon reference

* fix rewrite for onetwothree