AttributeError in make_default_short_help(None)

[davchaudhari]

Bug Description

click.utils.make_default_short_help() crashes with AttributeError when passed None. This can occur when programmatically creating commands where help text might not be provided, or when a developer passes None expecting the function to handle it gracefully.

Reproduction

from click.utils import make_default_short_help

# This crashes
result = make_default_short_help(None)

Full traceback:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "click/utils.py", line 62, in make_default_short_help
    paragraph_end = help.find("\n\n")
                    ^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'find'

Real-world scenario where this could happen:

@click.command()
@click.option('--help-text', default=None)
def my_command(help_text):
    # If help_text is None, this crashes
    short_help = make_default_short_help(help_text)

Expected Behavior

The function should either:

1. Return an empty string ("") when passed None, OR
2. Raise a clear TypeError with a message like "help must be a string, not NoneType"

Currently, the AttributeError doesn't clearly indicate that the problem is with the input validation.

Suggested Fix

Add input validation at the start of the function:

def make_default_short_help(help: str | None, max_length: int = 45) -> str:
    if help is None:
        return ""
    # ... rest of function

Environment:

• Python version: 3.13.1
• Click version: latest from main branch (tested with git clone)

[davidism]

Please do not use LLMs to generate bug reports for you.

That's why it's annotated to take str, not str | None. Use a type checker. Additionally, this is not a public API, so we make no guarantees about its availability or use.