Remove the redundant guard on the event loop

filter.go

@@ -120,10 +120,7 @@ func main() {
 	upperBound := min(ymax-3, len(*input))
 
 	// Event loop
-	for {
-		if done {
-			break
-		}
+	for !done {
 		s.Clear()
 		Render(s, input, lowerBound, upperBound, currentLine)