Syntax errors are not emitted in JSON format when using `--output=json`

[correctmost]

Bug Report

To Reproduce

Run mypy --output=json invalid.py

invalid.py

x:

Expected Behavior

The output can be parsed as JSON

Actual Behavior

The default output format is used:

invalid.py:1: error: Invalid syntax  [syntax]
Found 1 error in 1 file (errors prevented further checking)

Your Environment

• Mypy version used: mypy 1.20.2
• Mypy command-line flags: --output=json
• Mypy configuration options from mypy.ini (and other config files): N/A
• Python version used: 3.14.4

[AA-Turner]

On this topic, config errors (arguably diagnostics?) are always outputted as strings, regardless of --output=json: [mypy]: Unrecognized option: blah = spam