Add error handling in sinatra test app to catch additional mysql query errors
Add error handling in sinatra test app to catch additional mysql query errors

- to help identify the occurrence of a commonly-seen CI flakiness condition

cloudfoundry/cf-mysql-release,kbastani/cf-mysql-release,CloudCredo/cf-mysql-release,CloudCredo/cf-mysql-release,cloudfoundry/cf-mysql-release,ruanbinfeng/cf-mysql-release,cloudfoundry/cf-mysql-release,ruanbinfeng/cf-mysql-release,krishna-mk/cf-mysql-release,ruanbinfeng/cf-mysql-release,krishna-mk/cf-mysql-release,krishna-mk/cf-mysql-release,kbastani/cf-mysql-release,kbastani/cf-mysql-release,ruanbinfeng/cf-mysql-release,cloudfoundry/cf-mysql-release,CloudCredo/cf-mysql-release