improve error messages (closes #207)

pollen/private/ts.rktd

@@ -1 +1 @@
-1573328416
+1573398728

pollen/render.rkt

@@ -152,11 +152,18 @@
   (reset-mod-date-hash!)
   (define expanded-source-paths
     (let loop ([paths paths-in] [acc null])
-      (match (and (pair? paths) (->complete-path (car paths)))
-        [#false (sort (remove-duplicates acc) string<? #:key path->string)]
-        [(? pagetree-source? pt) (loop (append (pagetree->paths pt) (cdr paths)) acc)]
-        [(app ->source-path (and (not #false) (? file-exists?) sp)) (loop (cdr paths) (cons sp acc))]
-        [_ (loop (cdr paths) acc)])))
+      (match paths
+        [(? null?) (sort (remove-duplicates acc) string<? #:key path->string)]
+        [(cons path rest)
+         (match (->complete-path path)
+           [(? pagetree-source? pt)
+            (loop (append (pagetree->paths pt) rest) acc)]
+           [(app ->source-path (and (not #false) (? file-exists?) sp))
+            (loop rest (cons sp acc))]
+           [(or (? file-exists?) (? directory-exists?)) (loop rest acc)]
+           [unknown (raise-user-error 'render-batch
+                                      "~a is not a source path, directory, or output path"
+                                      unknown)])])))
   (cond
     [(null? expanded-source-paths) (message "[no paths to render]")]
     [wants-dry-run? (for-each message expanded-source-paths)]
@@ -196,7 +203,7 @@
   (define output-path (cond
                         [maybe-output-path]
                         [(->output-path source-path)]
-                        [else (raise-argument-error caller "valid output path" output-path)]))
+                        [else (raise-argument-error caller "valid output path" maybe-output-path)]))
   (define template-path (cond
                           [maybe-template-path]
                           [(get-template-for source-path output-path)]
@@ -320,17 +327,16 @@
     (cond
       [maybe-output-path]
       [(->output-path source-path)]
-      [else (raise-argument-error 'render-markup-or-markdown-source "valid output path" output-path)]))
+      [else (raise-argument-error 'render-markup-or-markdown-source "valid output path" maybe-output-path)]))
   (define template-path
     (cond
       [maybe-template-path]
       [(get-template-for source-path output-path)]
-      [else (raise-argument-error 'render-markup-or-markdown-source
-                                  (format "valid template path~a"
+      [else (raise-user-error 'render-markup-or-markdown-source
+                              "couldn't find template~a"
                               (if (has-inner-poly-ext? source-path)
-                                              (format " for target ~a" (current-poly-target))
-                                              ""))
-                                  template-path)]))
+                                  (format " for target .~a" (current-poly-target))
+                                  ""))]))
 
   ;; use a temp file so that multiple (possibly parallel) renders
   ;; do not compete for write access to the same template