Don't allow inserting empty codepoints

Author: LaurenzV

crates/krilla/src/object/font/cid_font.rs

@@ -103,7 +103,9 @@ impl CIDFont {
 
     #[inline]
     pub(crate) fn set_codepoints(&mut self, cid: Cid, text: String) {
-        self.cmap_entries.insert(cid, text);
+        if !text.is_empty() {
+            self.cmap_entries.insert(cid, text);
+        }
     }
 
     #[inline]
@@ -254,6 +256,7 @@ impl CIDFont {
             // For the .notdef glyph, it's fine if no mapping exists, since it is included
             // even if it was not referenced in the text.
             for g in 1..self.glyph_remapper.num_gids() {
+                println!("{:?}", self.cmap_entries.get(&g));
                 match self.cmap_entries.get(&g) {
                     None => sc.register_validation_error(ValidationError::InvalidCodepointMapping(
                         self.font.clone(),

crates/krilla/src/object/font/type3_font.rs

@@ -135,7 +135,9 @@ impl Type3Font {
 
     #[inline]
     pub(crate) fn set_codepoints(&mut self, gid: Gid, text: String) {
-        self.cmap_entries.insert(gid, text);
+        if !text.is_empty() {
+            self.cmap_entries.insert(gid, text);
+        }
     }
 
     #[inline]