MRGT error messages should help users identify and fix errors

[RieksJ]

The MRGT (as all other TEv2 tools) specifies that it should help me (the user) to

• identify the cause of the error, and subsequently
• help me fix it.

The following figures show

• a screenshot of me using the tool as specified in the browser's address bar; the scope directory location field contains the text https://ci.tno.nl/gitlab/T4SMM/documentation/-/tree/trrt-integration/, which points to (the scopedir in) a repo here at tno in gitlab, that contains a valid SAF as far as I can tell.
• a screenshot of the result, which is an error message that neither identifies the cause of the error, nor helps me fix it.

Figure 1

Figure 2