minSdkVersion 19 cannot be smaller than version 22
When you are facing this error during ionic project building, it is as a result that cordova does not set minSdkVersion and targetSdkVersion correctly in app apk.
This was due to a bug in firstname.lastname@example.org but now solved with cordova-android updated versions.
Updating to email@example.com is required when facing this issue and it is pretty simple in doing that.
Lunch terminal inside project folder and run these two commands to upgrade:
//first remove cordova platform android cordova platform remove android //install firstname.lastname@example.org or higher cordova platform add email@example.com
compile project again and it should work.
Read more about cordova versions from the official website