[FEATURE] Add a proper error handling

[airnst]

Description

In order to ensure the data transformation service to work in a stable and transparent fashion, appropriate error handling should be implemented for the following aspects:

• Check if 'service' parameter is present and handle its absence.
• Check if value in 'version' does not exist in DTS
• Check if latest version is deprecated. If so, reject transformation.
• Check if 'transformation' parameter is empty.
• Handling of URLs that include parameters or trailing slashes.
• Handling of unsupported engines.
• Proper error logging.

Open questions

Files

1. index.php

Tasks

• Implement respective handling code.
• Conduct tests.