Use crash! instead of user_error! on configuration access mis-use (fastlane#13766)

Since those methods are mostly used internally and for plugins, this will make debugging easier, as the crash will show the full stack trace, instead of just the error message

Author: KrauseFx

fastlane_core/lib/fastlane_core/configuration/configuration.rb

@@ -211,7 +211,7 @@ def self.find_configuration_file_path(config_file_name: nil)
     # if 'ask' is true and the value is not present, the user will be prompted to provide a value
     # rubocop:disable Metrics/PerceivedComplexity
     def fetch(key, ask: true)
-      UI.user_error!("Key '#{key}' must be a symbol. Example :app_id.") unless key.kind_of?(Symbol)
+      UI.crash!("Key '#{key}' must be a symbol. Example :app_id.") unless key.kind_of?(Symbol)
 
       option = verify_options_key!(key)
 
@@ -263,7 +263,7 @@ def fetch(key, ask: true)
     # Overwrites or sets a new value for a given key
     # @param key [Symbol] Must be a symbol
     def set(key, value)
-      UI.user_error!("Key '#{key}' must be a symbol. Example :#{key}.") unless key.kind_of?(Symbol)
+      UI.crash!("Key '#{key}' must be a symbol. Example :#{key}.") unless key.kind_of?(Symbol)
       option = option_for_key(key)
 
       unless option