feat: warn and exit non-zero when attempting to rebuild from a non-existent branch

Closes #4898

plugins/git/receive-app

@@ -3,4 +3,12 @@ source "$PLUGIN_AVAILABLE_PATH/git/functions"
 set -eo pipefail
 [[ $DOKKU_TRACE ]] && set -x
 
-git_receive_app "$@"
+trigger-git-receive-app() {
+  declare desc="builds the app from the local git repository"
+  declare trigger="receive-app"
+
+  git_receive_app "$@"
+  return $?
+}
+
+trigger-git-receive-app "$@"