Handle missing mixin folder.

bin/projectinator.rb

@@ -79,18 +79,21 @@ def lookup_yaml_extension(config:)
  # Pick apart a :mixins projcet configuration section and return components
  # Layout mirrors :plugins section
  def extract_mixins(config:, mixins_base_path:)
+ # Check if our base path exists
+ mixins_base_path = nil unless File.directory?(mixins_base_path)
+
  # Get mixins config hash
  _mixins = config[:mixins]
 
  # If no :mixins section, return:
  # - Empty enabled list
  # - Load paths with only the built-in Ceedling mixins/ path
- return [], [mixins_base_path] if _mixins.nil?
+ return [], [mixins_base_path].compact if _mixins.nil?
 
  # Build list of load paths
  # Configured load paths are higher in search path ordering
  load_paths = _mixins[:load_paths] || []
- load_paths += [mixins_base_path] # += forces a copy of configuration section
+ load_paths += [mixins_base_path].compact # += forces a copy of configuration section
 
  # Get list of mixins
  enabled = _mixins[:enabled] || []