[css-font-loading] Sentence fragment

Author: tabatkins

css-font-loading/Overview.bs

@@ -840,8 +840,9 @@ The <code>check()</code> method</h3>
 			as the text will be rendered in the UA's fallback font instead,
 			and won't trigger any font loads.
 		* If none of the specified fonts exist,
-			even though this is technically similar to the previous case,
-			in that text rendered with that font list would just use the UA fallback font.
+			even though this is technically similar to the previous case
+			(in that text rendered with that font list would just use the UA fallback font),
+			the method instead throws an error.
 			This is because such a situation is almost certainly either a typo,
 			or the result of changing the name of a downloadable font
 			and forgetting to update all places the old name was used,