Pull GeomSf linetype from GeomPolygon/GeomLine (#6661)

* pull `linetype` from GeomPolygon/GeomLine

* defend against character linetypes

* add news bullet

Author: teunbrand

NEWS.md

@@ -1,5 +1,7 @@
 # ggplot2 (development version)
 
+* The default linetype in `geom_sf()` is derived from `geom_polygon()` for 
+  polygons and from `geom_line()` for (multi)linestrings (@teunbrand, #6543).
 * Using infinite `radius` aesthetic in `geom_spoke()` now throws a warning 
   (#6671)
 * Scales and guides specified by a string can now use package name prefixes to

R/geom-sf.R

@@ -126,7 +126,7 @@ GeomSf <- ggproto("GeomSf", Geom,
     fill = NULL,
     size = NULL,
     linewidth = NULL,
-    linetype = from_theme(linetype),
+    linetype = NULL,
     alpha = NA,
     stroke = 0.5
   ),
@@ -200,6 +200,10 @@ GeomSf <- ggproto("GeomSf", Geom,
 
     # Recombine data in original order
     data <- vec_c(points, lines, others, collections)
+    # Avoids NA linetype in points, which is invalid input
+    data$linetype[vec_seq_along(points)] <-
+      if (is.character(data$linetype)) "solid" else 1L
+
     vec_slice(data, order(unlist(index)))
   },