fix: commands with actions without parameters (twilio#230)

`conversations:v1:configuration:fetch` command doesn't have
any parameter, therefore parameters property is not defined in
the OpenAPI spec.
This commit fixes the assumption that all the actions have parameters.

src/services/twilio-api/api-command-runner.js

@@ -66,7 +66,7 @@ class ApiCommandRunner {
 
   async execute() {
     const { domainName, path, actionName } = this.actionDefinition;
-    const actionParams = this.actionDefinition.action.parameters;
+    const actionParams = this.actionDefinition.action.parameters || [];
 
     logger.debug(`domainName=${domainName}, path=${path}, actionName=${actionName}`);