require(ggseas)
Easter_Sales <- read.csv("Easter Sales.csv", header=TRUE)
Easter_Sales$Date <- strptime(Easter_Sales$Date, "%m/%d/%Y")
ggsdc(Easter_Sales, aes(x = Date, y = Daily_Sales), method = c("stl", "decompose", "seas"), s.window = 7, type = c("additive", "multiplicative"),index.ref = NULL, start = c(2012,1), frequency = 7, facet.titles = c("observed", "trend", "seasonal", "irregular"))

Warning message:
In if (class(data[, xvar]) == "Date" & (is.null(frequency))) { :
the condition has length > 1 and only the first element will be used