Merge pull request #907 from kgrz/fix-error-with-rack-master

Update ShowExceptions to suit latest rack master

lib/sinatra/show_exceptions.rb

@@ -24,18 +24,24 @@ def call(env)
 
       if prefers_plain_text?(env)
         content_type = "text/plain"
-        body = [dump_exception(e)]
+        exception_string = dump_exception(e)
       else
         content_type = "text/html"
-        body = pretty(env, e)
+        exception_string = pretty(env, e)
       end
 
       env["rack.errors"] = errors
 
-      [500,
+      # Post 893a2c50 in rack/rack, the #pretty method above, implemented in
+      # Rack::ShowExceptions, returns a String instead of an array.
+      body = Array(exception_string)
+
+      [
+        500,
        {"Content-Type" => content_type,
         "Content-Length" => Rack::Utils.bytesize(body.join).to_s},
-       body]
+       body
+      ]
     end
 
     private