pkgs/lf-make-map: Don't assume `String::len` returns number of chars

It returns number of bytes, as such a char such as `Á` has a length of
2.

1 files changed, 1 insertions, 1 deletions

diff --git a/pkgs/by-name/lf/lf-make-map/src/mapping/map_key.rs b/pkgs/by-name/lf/lf-make-map/src/mapping/map_key.rs
index 10b612fd..5fd046fb 100644
--- a/pkgs/by-name/lf/lf-make-map/src/mapping/map_key.rs
+++ b/pkgs/by-name/lf/lf-make-map/src/mapping/map_key.rs
@@ -157,7 +157,7 @@ This should not happen, please report the bug!",
         };
 
         assert_eq!(
-            value.len(),
+            value.chars().count(),
             number_of_chars,
             "'{}' does not have expected length of: {}",
             value,