#399

backend/app/services/post_import_previewer.rb

@@ -47,10 +47,9 @@ class PostImportPreviewer
         attributes[field] = value
         provenance[field] = 'automatic'
       end
-      post = Post.new(url:)
-      post.valid?
-      normal_url = post.url
-      errors = post.errors.to_hash.transform_values(&:dup)
+      normal_url = normalised_url(url)
+      errors = { }
+      errors[:url] = ['URL が不正です．'] if normal_url.blank?
       validation_warnings = []
       errors[:url] = ['URL が重複しています．'] if normal_url.present? && urls.key?(normal_url)
       urls[normal_url] = true if normal_url.present?
@@ -165,6 +164,7 @@ class PostImportPreviewer
                     video_ms: parse_duration(attributes['duration'], errors))
     post.valid?
     post.errors.each { |error| (errors[error.attribute] ||= []) << error.message }
+    errors.delete(:url)
   end
 
   def parse_duration value, errors