Remove obsolete cgen of Optional effects

This if-else branch was obsoleted by commit 1ea32b37.
diff --git a/internal/cgen/statement.go b/internal/cgen/statement.go
index c0c1b8a..9e96cfe 100644
--- a/internal/cgen/statement.go
+++ b/internal/cgen/statement.go
@@ -146,8 +146,6 @@
 				return false, err
 			}
 			b.writes("status = ")
-		} else if rhs.Effect().Coroutine() {
-			b.writes("status = ")
 		}
 
 		if !hack {