API: Load casks/formula from JSON with missing keys

We'd like to reduce the size of the API JSON and to do that we are
going to remove unused and/or blank elements from the cask/formula
definition. This will reduce the amount of data that has to go
over the wire and make it easier to load this data into memory.

Library/Homebrew/api.rb

@@ -124,11 +124,12 @@ module Homebrew
 
     sig { params(json: Hash).returns(Hash) }
     def self.merge_variations(json)
+      return json unless json.key?("variations")
+
       bottle_tag = ::Utils::Bottles::Tag.new(system: Homebrew::SimulateSystem.current_os,
                                              arch:   Homebrew::SimulateSystem.current_arch)
 
-      if (variations = json["variations"].presence) &&
-         (variation = variations[bottle_tag.to_s].presence)
+      if (variation = json.dig("variations", bottle_tag.to_s).presence)
         json = json.merge(variation)
       end
 

Library/Homebrew/cask/cask.rb

@@ -279,7 +279,7 @@ module Cask
     def populate_from_api!(json_cask)
       raise ArgumentError, "Expected cask to be loaded from the API" unless loaded_from_api?
 
-      @languages = json_cask[:languages]
+      @languages = json_cask.fetch(:languages, [])
       @tap_git_head = json_cask.fetch(:tap_git_head, "HEAD")
 
       @ruby_source_path = json_cask[:ruby_source_path]

Library/Homebrew/cask/cask_loader.rb

@@ -280,7 +280,7 @@ module Cask
 
           url json_cask[:url], **json_cask.fetch(:url_specs, {}) if json_cask[:url].present?
           appcast json_cask[:appcast] if json_cask[:appcast].present?
-          json_cask[:name].each do |cask_name|
+          json_cask[:name]&.each do |cask_name|
             name cask_name
           end
           desc json_cask[:desc]

Library/Homebrew/formulary.rb

@@ -154,14 +154,14 @@ module Formulary
 
     json_formula = Homebrew::API.merge_variations(json_formula)
 
-    uses_from_macos_names = json_formula["uses_from_macos"].map do |dep|
+    uses_from_macos_names = json_formula["uses_from_macos"]&.map do |dep|
       next dep unless dep.is_a? Hash
 
       dep.keys.first
     end
 
     requirements = {}
-    json_formula["requirements"].map do |req|
+    json_formula["requirements"]&.map do |req|
       req_name = req["name"].to_sym
       next if API_SUPPORTED_REQUIREMENTS.exclude?(req_name)
 
@@ -176,7 +176,7 @@ module Formulary
 
       req_tags = []
       req_tags << req_version if req_version.present?
-      req_tags += req["contexts"].map do |tag|
+      req_tags += req["contexts"]&.map do |tag|
         case tag
         when String
           tag.to_sym
@@ -202,7 +202,7 @@ module Formulary
 
       dep_json = json_formula.fetch("#{spec}_dependencies", json_formula)
 
-      dep_json["dependencies"].each do |dep|
+      dep_json["dependencies"]&.each do |dep|
         # Backwards compatibility check - uses_from_macos used to be a part of dependencies on Linux
         next if !json_formula.key?("uses_from_macos_bounds") && uses_from_macos_names.include?(dep) &&
                 !Homebrew::SimulateSystem.simulating_or_running_on_macos?
@@ -211,7 +211,7 @@ module Formulary
       end
 
       [:build, :test, :recommended, :optional].each do |type|
-        dep_json["#{type}_dependencies"].each do |dep|
+        dep_json["#{type}_dependencies"]&.each do |dep|
           # Backwards compatibility check - uses_from_macos used to be a part of dependencies on Linux
           next if !json_formula.key?("uses_from_macos_bounds") && uses_from_macos_names.include?(dep) &&
                   !Homebrew::SimulateSystem.simulating_or_running_on_macos?
@@ -220,7 +220,7 @@ module Formulary
         end
       end
 
-      dep_json["uses_from_macos"].each_with_index do |dep, index|
+      dep_json["uses_from_macos"]&.each_with_index do |dep, index|
         bounds = dep_json.fetch("uses_from_macos_bounds", [])[index] || {}
         bounds.deep_transform_keys!(&:to_sym)
         bounds.deep_transform_values! { |val| val.is_a?(String) ? val.to_sym : val }
@@ -311,7 +311,7 @@ module Formulary
         disable! date: disable_date, because: reason
       end
 
-      json_formula["conflicts_with"].each_with_index do |conflict, index|
+      json_formula["conflicts_with"]&.each_with_index do |conflict, index|
         conflicts_with conflict, because: json_formula.dig("conflicts_with_reasons", index)
       end