[ttGlyphSet] Only decompose VarComposites on AttributeError

Keep NotImplementedError for clients to really say don't want it.

Lib/fontTools/pens/recordingPen.py

@@ -102,9 +102,6 @@ class DecomposingRecordingPen(DecomposingPen, RecordingPen):
             b: [('moveTo', ((-1, 1),)), ('curveTo', ((0, 2), (1, 3), (2, 4))), ('closePath', ())]
     """
 
-    def addVarComponent(self, glyphName, transformation, location):
-        raise NotImplementedError
-
     # raises KeyError if base glyph is not found in glyphSet
     skipMissingComponents = False
 

Lib/fontTools/ttLib/ttGlyphSet.py

@@ -194,7 +194,7 @@ class _TTGlyphGlyf(_TTGlyph):
                     pen.addVarComponent(
                         comp.glyphName, comp.transform, self.glyphSet.rawLocation
                     )
-                except (NotImplementedError, AttributeError):
+                except AttributeError:
                     t = comp.transform.toTransform()
                     if isPointPen:
                         tPen = TransformPointPen(pen, t)