warn when config fails to load

lib/chibi/config.scm

@@ -111,7 +111,11 @@
      (else (lp (cdr ls) (cons (car ls) rev))))))
 
 (define (read-from-file file . opt)
-  (guard (exn (else (and (pair? opt) (car opt))))
+  (guard (exn
+          (else
+           (warn "couldn't load config:" file)
+           (print-stack-trace exn)
+           (and (pair? opt) (car opt))))
     (call-with-input-file file read)))
 
 (define (alist? x)

lib/chibi/config.sld

@@ -10,6 +10,17 @@
   ;; This is only used for config verification, it's acceptable to
   ;; substitute file existence for the stronger directory check.
   (cond-expand
-   (chibi (import (only (chibi filesystem) file-directory?)))
-   (else (begin (define file-directory? file-exists?))))
+   (chibi
+    (import (only (meta) warn))
+    (import (only (chibi) print-stack-trace))
+    (import (only (chibi filesystem) file-directory?)))
+   (else
+    (begin
+      (define file-directory? file-exists?)
+      (define (print-stack-trace . o) #f)
+      (define (warn msg . args)
+        (let ((err (current-error-port)))
+          (display msg err)
+          (for-each (lambda (x) (display " " err) (write x err)) args)
+          (newline err))))))
   (include "config.scm"))