`onyo new` errors if no `--template` is specified

[TobiasKadelka]

I tried to create 3 assets at once, only specifying type, make, model and faux serials. It did error, stating the "empty" template (containing only the ---) is causing a problem:

(onyo) tkadelka@bnbmac73 in ~/inventory on git:spss
❱ onyo --version                                                                                  1 !
onyo 0.5.1.dev249+g648cd9b
❱ onyo new --keys type=license make=ibm model.name=spss_base_edition model.name=spss_custom_tables_advanced_statistics model.name=spss_complex_sampling_testing serial=faux --directory <censored>
ERROR: Invalid item in YAML document (/Users/tkadelka/inventory/.onyo/templates/empty).

This might be fixed in the open PRs that rework onyo new. But either way I wanted to create this issue as a reminder to verify in the future that this works. (The error message does not really help me either to identify what the item is which seems to be invalid.)