sinatra.error #<TypeError: no implicit conversion of nil into String>

[robertocabellon]

After adding a first path to gitdocs server it gets into error state, showing the following message:

sinatra.error	
#<TypeError: no implicit conversion of nil into String>

rack.errors	
#<Object:0x00000000ff5410>
rack.input	
#<StringIO:0x00000002c5b960>

sinatra.accept	
[#<Sinatra::Request::AcceptEntry:0x00000002c0c090 @entry="text/html", @type="text/html", @params={}, @q=1.0>, #<Sinatra::Request::AcceptEntry:0x00000002c07e50 @entry="application/xhtml+xml", @type="application/xhtml+xml", @params={}, @q=1.0>, #<Sinatra::Request::AcceptEntry:0x00000002c078b0 @entry="image/webp", @type="image/webp", @params={}, @q=1.0>, #<Sinatra::Request::AcceptEntry:0x00000002c07c98 @entry="application/xml;q=0.9", @type="application/xml", @params={}, @q=0.9>, #<Sinatra::Request::AcceptEntry:0x00000002c076f8 @entry="*/*;q=0.8", @type="*/*", @params={}, @q=0.8>]
sinatra.error	
#<TypeError: no implicit conversion of nil into String>
sinatra.route	
GET /:id*

You're seeing this error because you have enabled the show_exceptions setting.

The server returns to normal state after removing the path.

(I've tried with several (relative and absolute) paths)