Labels of `type_text()` should automically inherit `y` values if not provided

[grantmcdermott]

To be consistent with base text():

plot(1:10, type = "n")
text(1:10)

The equivalent tinyplot call fails:

library(tinyplot)
plt(1:10, type = "text")
#> Error: argument "labels" is missing, with no default

^{Created on 2025-09-27 with reprex v2.1.1}