Message text, for errors and other feedback

Error messages

Error text should be succinct and unambiguous. The nature of the error should be described first, followed by additional information such as the rule which has not been met or the reason for the error, then lastly the recommended action for the user: 

[the error][the rule / reason for the error][the recommended action]

Important information such as filename, fieldnames and counts should be highlighted in bold.

Examples: 

a-different-file.csv has no content. The file must not be empty. Please select a file with content

A-different-file.csv is 11.4 MB. Maximum file size is 10 MB. Please select a smaller file

a-file-name.pdf is in an unsupported format. Valid formats are CSV and TSV. Please select a file in a valid format