astutil: do not crash if the AST is just a token

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/src/astutil.nit b/src/astutil.nit
index c671e87..7257c3f 100644 (file)
--- a/src/astutil.nit
+++ b/src/astutil.nit
@@ -278,13 +278,13 @@ private class PTokenVisitor
                else
                        p = last_token.common_parent(n)
                end
-               assert p isa Prod
-
-               # And apply it to detached tokens between `last_token` and `n`
-               var c = n.prev_token
-               while c != null and c.parent == null do
-                       c.parent = p
-                       c = c.prev_token
+               if p isa Prod then
+                       # And apply it to detached tokens between `last_token` and `n`
+                       var c = n.prev_token
+                       while c != null and c.parent == null do
+                               c.parent = p
+                               c = c.prev_token
+                       end
                end
 
                self.last_token = n