Fixed an uncought exception when run on the Google App Engine infrastructure.

Signed-off-by: Simon Rozet <simon@rozet.name>

lib/sinatra/base.rb

@@ -635,7 +635,14 @@ module Sinatra
       # when no file is specified.
       def use_in_file_templates!(file=nil)
         file ||= caller_files.first
-        if data = ::IO.read(file).split('__END__')[1]
+
+        begin
+          data = ::IO.read(file).split('__END__')[1]
+        rescue
+          data = nil
+        end
+
+        if data
           data.gsub!(/\r\n/, "\n")
           template = nil
           data.each_line do |line|

test/templates_test.rb

@@ -75,6 +75,16 @@ class TemplatesTest < Test::Unit::TestCase
     assert_equal "this is foo\n\n", @app.templates[:foo]
     assert_equal "X\n= yield\nX\n", @app.templates[:layout]
   end
+
+  test 'use_in_file_templates simply ignores IO errors' do
+    assert_nothing_raised {
+      mock_app {
+        use_in_file_templates!('/foo/bar')
+      }
+    }
+
+    assert @app.templates.empty?
+  end
 end
 
 __END__