Error messages need consistency improvements

[stefanblaginov]

Bug Report 🐛

The current error messages originating from concerto-core have a few inconsistencies that need to improved. Often it's unclear if a part of the error message description refers to a natural language word or a term or value used by Concerto.

Possible Solution

The following principles should be followed when in comes to error messages:

• Terms should be surrounded by double quotation marks, common to US English. In this context, terms are all words that represent code, parts or snippets of Concerto and differ from the complementing explanatory text in the message.
• Full stops at the end of error message (detail) sentences should be added in order to provide a consistent error format. The reasoning behind this is that error messages (details) are proper sentences, rather than just titles. Some discussions on the topic:
  https://ux.stackexchange.com/questions/18671/periods-at-the-end-of-a-sentence-in-alert-message
  https://stackoverflow.com/questions/1136829/do-you-end-your-exception-messages-with-a-period
• Occurrences of "super type" should be replaced with "supertype", which seems to be widely used.
• Consistency should be improved when it comes to terms surrounded by parentheses.
• The "telegraph-ese" style of messages should be foregone and grammatical articles should be used.
• Sentence ambiguity should be removed.