play: Fix crash when exception stack frame is from an unknown file.

1 files changed, 5 insertions, 1 deletions

diff --git a/chickadee/cli/play.scm b/chickadee/cli/play.scm
index 4e18b31..7c3fed1 100644
--- a/chickadee/cli/play.scm
+++ b/chickadee/cli/play.scm
@@ -203,7 +203,11 @@ Resume the game loop without entering a debugger."
               (format #f "~a: In procedure: ~a:~%In procedure: ~a: ~a~%"
                       (match (frame-source frame)
                         ((_ file-name line . column)
-                         (format #f "~a:~a:~a" (basename file-name) line column))
+                         (format #f "~a:~a:~a"
+                                 (if file-name
+                                     (basename file-name)
+                                     "unknown file")
+                                 line column))
                         (_ "unknown"))
                       (frame-procedure-name frame)
                       (if (exception-with-origin? e)