Malformed @click links crash Textual application

[xavierog]

Context

I was just trying out the @click syntax.

Expected behaviour

If I create e.g. a Label with incorrect markup, I should get a MarkupError immediately.

Current behaviour

Some @click syntax do not raise a MarkupError and make Textual applications crash when clicked, namely:

• [@click]
• [@click=]
• [@click=()]

MRE:

#!/usr/bin/env python3
from textual.app import App, ComposeResult
from textual.widgets import Label

class ClickMRE(App):
    def compose(self) -> ComposeResult:
        yield Label("[@click]click me and crash[/]") # ValueError in run_action on click
        yield Label("[@click=]click me and crash[/]") # ValueError in run_action on click
        yield Label("[@click=()]click me and crash[/]") # ValueError in run_action on click
        #yield Label("[@click=(,)]click me and crash[/]") # MarkupError in render at startup
        yield Label("[@click=foobar]click me[/]") # ok, nothing happens
        yield Label("[@click=foobar()]click me[/]") # ok, nothing happens
        yield Label("[@click=toggle_dark]click me[/]") # ok, works fine
        yield Label("[@click=toggle_dark()]click me[/]") # ok, works fine

if __name__ == "__main__":
    app = ClickMRE()
    app.run()

Textual Diagnostics

Versions

Name	Value
Textual	0.52.1
Rich	13.7.0

Python

Name	Value
Version	3.11.8
Implementation	CPython
Compiler	GCC 13.2.0
Executable	~/whatever/venv/bin/python3

Operating System

Name	Value
System	Linux
Release	6.6.15-amd64
Version	#1 SMP PREEMPT_DYNAMIC Debian 6.6.15-2 (2024-02-04)

Terminal

Name	Value
Terminal Application	tmux (3.4)
TERM	xterm-256color
COLORTERM	truecolor
FORCE_COLOR	Not set
NO_COLOR	Not set

Rich Console options

Name	Value
size	width=212, height=34
legacy_windows	False
min_width	1
max_width	212
is_terminal	False
encoding	utf-8
max_height	34
justify	None
overflow	None
no_wrap	False
highlight	None
markup	None
height	None

[willmcgugan]

Those aren't broken markup per se. But obviously it shouldn't crash Textual...

[xavierog]

FWIW, my current workaround is:

        text = self.render_str(value)
        # Extra check to work around https://github.com/Textualize/textual/issues/4248:
        for span in text.spans:
            if hasattr(span.style, 'meta') and span.style.meta.get('@click') == ():
                raise MarkupError('problematic @click tag')

[github-actions]

Don't forget to star the repository!

Follow @textualizeio for Textual updates.

[xavierog]

I confirm I can no longer reproduce the issue as of textual 0.54.0.