Extremely opaque error message for layout '*', :erb

[whitequark]

To reproduce, let's have no content and just this in Rules:

layout '*', :erb

Running nanoc gives:

Crashlog created at 2016-07-21 04:47:39 +0000

===== MESSAGE:

NoMethodError: undefined method `[]' for nil:NilClass

===== COMPILATION STACK:

  (empty)

===== STACK TRACE:

  0. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/rule_dsl/rule_memory_calculator.rb:88:in `block in new_rule_memory_for_layout'
  1. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/rule_dsl/rule_memory_calculator.rb:87:in `tap'
  2. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/rule_dsl/rule_memory_calculator.rb:87:in `new_rule_memory_for_layout'
  3. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/rule_dsl/rule_memory_calculator.rb:36:in `[]'
  4. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/base/memoization.rb:87:in `block in memoize'
  5. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/rule_dsl/action_provider.rb:36:in `memory_for'
  6. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/base/compilation/compiler.rb:114:in `block in store'
  7. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/base/compilation/compiler.rb:113:in `each'
  8. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/base/compilation/compiler.rb:113:in `store'
  9. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/base/compilation/compiler.rb:90:in `run'
  10. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/base/compilation/compiler.rb:77:in `run_all'
  11. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/base/entities/site.rb:30:in `compile'
  12. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/cli/commands/compile.rb:367:in `block in run'
  13. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/cli/commands/compile.rb:409:in `run_listeners_while'
  14. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/cli/commands/compile.rb:366:in `run'
  15. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/cli/command_runner.rb:12:in `block in call'
  16. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/cli/error_handler.rb:64:in `handle_while'
  17. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/cli/error_handler.rb:22:in `handle_while'
  18. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/cli/command_runner.rb:11:in `call'
  19. /home/whitequark/.gem/ruby/2.3.0/gems/cri-2.7.0/lib/cri/command_dsl.rb:233:in `block in runner'
  20. /home/whitequark/.gem/ruby/2.3.0/gems/cri-2.7.0/lib/cri/command.rb:294:in `run_this'
  21. /home/whitequark/.gem/ruby/2.3.0/gems/cri-2.7.0/lib/cri/command.rb:247:in `run'
  22. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/cli/commands/nanoc.rb:37:in `block in define'
  23. /home/whitequark/.gem/ruby/2.3.0/gems/cri-2.7.0/lib/cri/command.rb:294:in `run_this'
  24. /home/whitequark/.gem/ruby/2.3.0/gems/cri-2.7.0/lib/cri/command.rb:247:in `run'
  25. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/cli.rb:53:in `block in run'
  26. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/cli/error_handler.rb:64:in `handle_while'
  27. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/cli/error_handler.rb:22:in `handle_while'
  28. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/lib/nanoc/cli.rb:51:in `run'
  29. /home/whitequark/.gem/ruby/2.3.0/gems/nanoc-4.2.3/bin/nanoc:9:in `<top (required)>'
  30. /home/whitequark/.gem/ruby/2.3.0/bin/nanoc:23:in `load'

There is no indication of what's wrong whatsoever. This is not good.

[Bike]

the direct site of the error mentions this problem as a potential, i feel i should mention (I am the one who ran into this but I have very little nanoc experience)

[denisdefreyne]

Oh, facepalm. res being nil will indeed throw a weird error (it’s still an erroneous condition, but the message could be far more helpful).

[denisdefreyne]

Fixed in #916.