Lottie: leave blank font families out of the embedded glyphs warning

A `chars` entry with an empty or whitespace-only `fFamily` listed an
empty name, so the warning read "of Sans, , Serif".

crates/lottie/src/import.rs

@@ -138,7 +138,7 @@ pub fn import(
     // Glyph outlines embedded for players without the fonts. Text is set in installed fonts.
     if let Some(chars) = doc.get("chars").and_then(Json::as_array).filter(|c| !c.is_empty()) {
         let mut fams: Vec<&str> = vec![];
-        for fam in chars.iter().filter_map(|c| s(c, "fFamily")) {
+        for fam in chars.iter().filter_map(|c| s(c, "fFamily")).filter(|f| !f.trim().is_empty()) {
             if !fams.contains(&fam) {
                 fams.push(fam);
             }

crates/lottie/src/tests.rs

@@ -525,10 +525,12 @@ fn embedded_glyphs_are_reported_when_dropped() {
     let glyph = |ch: &str, fam: &str| json!({"ch": ch, "size": 100, "style": "Regular", "w": 60, "fFamily": fam, "data": {"shapes": []}});
     let doc = json!({"w": 20, "h": 20, "fr": 30, "ip": 0, "op": 30, "assets": [], "layers": [],
         "fonts": {"list": [{"fName": "Sans-Regular", "fFamily": "Sans", "fStyle": "Regular"}]},
-        "chars": [glyph("A", "Sans"), glyph("B", "Sans"), glyph("C", "Serif")]});
-    let mut q = Project::default();
-    let imp = import(&mut q, doc.to_string().as_bytes(), "Imported", "", &mut |_| None).unwrap();
-    assert_eq!(imp.warnings, ["embedded glyphs (`chars`) of Sans, Serif are not imported; text uses the installed fonts"]);
+        "chars": [glyph("A", "Sans"), glyph("B", ""), glyph("C", "Serif")]});
+    let warnings = |doc: &Json| import(&mut Project::default(), doc.to_string().as_bytes(), "Imported", "", &mut |_| None).unwrap().warnings;
+    // A blank family name is left out, not listed as "of , …".
+    assert_eq!(warnings(&doc), ["embedded glyphs (`chars`) of Sans, Serif are not imported; text uses the installed fonts"]);
+    let blank = json!({"w": 20, "h": 20, "fr": 30, "layers": [], "chars": [glyph("A", " ")]});
+    assert_eq!(warnings(&blank), ["embedded glyphs (`chars`) are not imported; text uses the installed fonts"]);
 }
 
 #[test]