Gracefully fail pre-install for missing languages

Author: pdarragh

langs/installer.rkt

@@ -7,18 +7,19 @@
   (define lang-name
     (let-values ([(b f d?) (split-path own)])
       (path->string f)))
-  
+
   (main (path->string (collection-file-path "src/" "ziggy")) own
-        (cdr (assoc lang-name '(#;("abscond"   . "A")
-                                #;("blackmail" . "B")
-                                #;("con"       . "C")
-                                #;("dupe"      . "D0")
-                                ("dodger"    . "D1")
-                                ("evildoer"  . "E0")
-                                ("extort"    . "E1")
-                                ("fraud"     . "F")
-                                ("hustle"    . "H0")
-                                ("hoax"      . "H1")
-                                ("iniquity"  . "I")
-                                ("jig"       . "J")
-                                ("knock"     . "K"))))))
+        (cdr (or (assoc lang-name '(#;("abscond"   . "A")
+                                    #;("blackmail" . "B")
+                                    #;("con"       . "C")
+                                    #;("dupe"      . "D0")
+                                    ("dodger"    . "D1")
+                                    ("evildoer"  . "E0")
+                                    ("extort"    . "E1")
+                                    ("fraud"     . "F")
+                                    ("hustle"    . "H0")
+                                    ("hoax"      . "H1")
+                                    ("iniquity"  . "I")
+                                    ("jig"       . "J")
+                                    ("knock"     . "K")))
+                 (error 'ziggy-pre-installer (format "unsupported lang: ~s" lang-name))))))