Only print the names of the aesthetics with mismatched length (#2853)

* Only print the names of the aesthetics with mismatched length

* Add NEWS.md bullet

Author: karawoo

NEWS.md

@@ -1,5 +1,9 @@
 # ggplot2 3.0.0.9000
 
+*   The error message in `compute_aesthetics()` now provides the names of only
+    aesthetics with mismatched lengths, rather than all aesthetics (@karawoo,
+    #2853).
+
 *   `geom_sf()` now respects `lineend`, `linejoin`, and `linemitre` parameters 
     for lines and polygons (@alistaire47, #2826)
 

R/geom-.r

@@ -184,7 +184,7 @@ check_aesthetics <- function(x, n) {
 
   stop(
     "Aesthetics must be either length 1 or the same as the data (", n, "): ",
-    paste(names(!good), collapse = ", "),
+    paste(names(which(!good)), collapse = ", "),
     call. = FALSE
   )
 }