Added check for scrbl directory existence

Makefile.rkt

@@ -9,7 +9,8 @@
 (target clean
         (for-each (λ (f) (displayln f) (rm-f f)) (list-files "." #px"([.]bak|~)$" #:recursive #t))
         (for-each (λ (d) (displayln d) (rm-rf d)) (list-dirs "." #px"(compiled|doc)$" #:recursive #t))
-        (for-each (λ (f) (displayln f) (rm-f f)) (list-files "scrbl" #px"[.](css|js|html)$"))
+        (when (directory-exists? "scrbl")
+          (for-each (λ (f) (displayln f) (rm-f f)) (list-files "scrbl" #px"[.](css|js|html)$")))
         )
 
 (target package
@@ -28,7 +29,6 @@
             (displayln "Pushing...")
             (dgit 'push)))
         )
-        
 
 (target windows
         (deps housekeeping)