plantuml rendering shows blank screen on error

[abulka]

Should show error image instead, which at least gives an indication that there was an error and why. Or detect response 400 and display something meaningful

Example log file:

[Thu 10:35 am] [INFO] __main__ - 741 - image_url of UML http://www.plantuml.com/plantuml/png/Iyv9B2vMS5Ievb9GA4XCJoq6qhcf9HdvAOOQcborN5p9O0N1UOa5RfavgM6PgUL6Ba3LN4XocRa5EQaU9IK58Od5sM2JadCoK_DAu4O16QL5EKXQe0gHH4BpilFoo_CKGYeBKc4oQ9RQwEe27Sg5PfskReqTn3mk53D0gj6KSW40
[Thu 10:35 am] [INFO] common.gui_imageviewer - 155 - (2nd, image grabbing) Response from plant_uml_server status_code 400
[Thu 10:35 am] [ERROR] common.gui_imageviewer - 165 - Error getting plantuml IMAGE, (bad response 400)

[abulka]

Caused by Pynsource creating a class with a space character Unknown Type from this syntax:

class SimpleHttpTask(Task):
    url = None
    method = "GET"
    client: requests.Session = requests.Session()

See issue #85