Use f-string type conversion !r in error messages

[Copilot]

Updated remaining instances of manual quote formatting to use !r type conversion for consistency with the rest of the codebase.

Changes

pygmt/helpers/decorators.py (2 docstring examples)

• f"'{k}': {repr(kwargs[k])}" → f"{k!r}: {kwargs[k]!r}"

pygmt/tests/test_clib_loading.py (10 test patterns)

• Test expectations and mock error messages updated to match !r format
• Regex patterns: rf"Error loading '{var}'" → rf"Error loading {var!r}"

Example

# Before
", ".join(f"'{k}': {repr(kwargs[k])}" for k in sorted(kwargs))
msg = rf"Error loading '{libgmt}'. Couldn't access function GMT_Create_Session."

# After
", ".join(f"{k!r}: {kwargs[k]!r}" for k in sorted(kwargs))
msg = rf"Error loading {libgmt!r}. Couldn't access function GMT_Create_Session."

This completes the conversion started in earlier commits, ensuring all error messages and test patterns use the more concise !r syntax.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Use f-string type conversion !r in error messages to avoid single quotes</issue_title>
<issue_description>Currently, the error messages are in the following style:

>>> arg = "invalid"
>>> msg = f"Invalid value: '{arg}'."
>>> print(msg)
Invalid value: 'invalid'.

>>> arg = 10
>>> msg = f"Invalid value: '{arg}'."
>>> print(msg)
Invalid value: '10'.

>>> arg = None
>>> msg = f"Invalid value: '{arg}'."
>>> print(msg)
Invalid value: 'None'.

The cons are:

• Extra single quotes in f-strings
• Values are always enclosed in single quotes, regardless of the types

I propose to use type conversion !r in the new style:

>>> arg = "invalid"
>>> msg = f"Invalid value: {arg!r}."
>>> print(msg)
Invalid value: 'invalid'.

>>> arg = 10
>>> msg = f"Invalid value: {arg!r}."
>>> print(msg)
Invalid value: 10.

>>> arg = None
>>> msg = f"Invalid value: {arg!r}."
>>> print(msg)
Invalid value: None.

>>> arg = [10, 20, 30]
>>> msg = f"Invalid value: {arg!r}."
>>> print(msg)
Invalid value: [10, 20, 30].

👍 if you like new style; 👎 if you like the old style; or leave your comments.
</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Use f-string type conversion !r in error messages to avoid single quotes #3983

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[seisman]

This PR is made by Copilot, and it looks pretty good.