For those interested, funding gaps only really became a thing in the 1970's, during Ford's administration [0]. It wasn't until a new interpretation of the Anti-Deficiency Act of 1880 that they became known as "shutdowns" in 1980 [1]. So a relatively recent phenomenon.
Hilariously, prior to that law, the executive branch would overspend early in the year, forcing more spending from congress in order to meet their contracts [2].