Hotfix: parse oid when only one given

The function `show_detail` for courses was expecting an array of
lecturer oids. When it got only one and therefore not an array but an
int, the line `@lecturers_oid.each` would fail to parse the variable
because it is not an array.

app/controllers/crawlers/courses_crawler_controller.rb

@@ -29,12 +29,20 @@ class Crawlers::CoursesCrawlerController < Crawlers::TissCrawlerController
     @lecturers_oid = @course['lecturers']['oid']
     @lecturers_names = []
 
+    puts @lecturers_oid
+
     if @lecturers_oid != nil
+      if @lecturers_oid.is_a?(Array)
+        # In case @lecturers_oid contains multiple items
         @lecturers_oid.each do |item|
           # For each org id get the associated name
           puts TissCrawler.get_oid_name(item)
           @lecturers_names << (TissCrawler.get_oid_name(item))
         end
+      else
+        # In case @lecturers_oid only contains one item
+        @lecturers_names << (TissCrawler.get_oid_name(@lecturers_oid))
+      end
     end
 
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