[opentype/monospace] Ensure check works with monospace OTF fonts

(PR #5051)

Author: PeterDekkers

CHANGELOG.md

@@ -1,6 +1,12 @@
 Below are the noteworthy changes from each release.
 A more detailed list of changes is available in the corresponding milestones for each release in the Github issue tracker (https://github.com/googlefonts/fontbakery/milestones?state=closed).
 
+## Upcoming release v1.1.1 (2025-Oct-?)
+
+### Changes to existing checks
+#### On the OpenType profile
+  - **[opentype/monospace]**: Ensure check works with monospace OTF fonts (PR #5051)
+
 ## 1.1.0 (2025-Oct-02)
   - Replace deprecated `pkg_resources` by `importlib.resources` (issue #5028)
 

Lib/fontbakery/checks/opentype/monospace.py

@@ -166,10 +166,11 @@ def check_monospace(ttFont, glyph_metrics_stats):
                 f"{PANOSE_expected(family_type)}",
             )
 
-        num_glyphs = len(ttFont["glyf"].glyphs)
+        glyph_names = ttFont.getGlyphNames()
+        num_glyphs = len(glyph_names)
         unusually_spaced_glyphs = [
             g
-            for g in ttFont["glyf"].glyphs
+            for g in glyph_names
             if g not in [".notdef", ".null", "NULL"]
             and ttFont["hmtx"].metrics[g][0] != 0
             and ttFont["hmtx"].metrics[g][0] != most_common_width