Don't try to modify something that doesn't exist

diff --git a/src/InfoCon/buch/infocon b/src/InfoCon/buch/infocon
index 35b9d8e..9aa76c6 100755 (executable)
--- a/src/InfoCon/buch/infocon
+++ b/src/InfoCon/buch/infocon
@@ -237,7 +237,7 @@ sub read_input
     } elsif ($ans eq ".") {
        $ans = '';
     }
-    $ans =~ s/ *$//;
+    $ans =~ s/ *$// if $ans;
     return $ans;
 }