`type-arg` errors are over a larger node than necessary

[A5rocks]

Bug Report

Inspired by #18530, I tried using --pretty on a file with [type-arg]. Unfortunately the output isn't immediately understandable.

To Reproduce

import typing

x: typing.List[typing.List[int, int]] = []

Expected Behavior

repro.py:3: error: "list" expects 1 type argument, but 2 given  [type-arg]
    x: typing.List[typing.List[int, int]] = []
                   ^~~~~~~~~~~~~~~~~~~~~
Found 1 error in 1 file (checked 1 source file)

Actual Behavior

repro.py:3: error: "list" expects 1 type argument, but 2 given  [type-arg]
    x: typing.List[typing.List[int, int]] = []
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Found 1 error in 1 file (checked 1 source file)

Your Environment

• Mypy version used: v1.14.1
• Mypy command-line flags: --warn-unreachable
• Mypy configuration options from mypy.ini (and other config files): none, I think
• Python version used: 3.13.1