Duplicate parsing errors should be grouped based on line and colum.

[philipsens]

Is your feature request related to a problem? Please describe.
If you don't close a tag properly, saxes will throw a parse error for each character that "isn't supposed to be there".

Describe the solution you'd like
There should be one error message stating a start line and end line in which the error occurred.

Describe alternatives you've considered
@chiefruds: Alternatively for filtering the errors in the canvas you can also filter the errors here on the line and only add one unique error for each line.

Additional context
Discussion started: #173