Bug report

Bug description:

Python version: Python 3.14.0a7+ (heads/main-dirty:8d0e07eb899.

To reproduce type the following class definition in the REPL:

class C:
    def
    m

Then set the cursor to the space before m and press backspace to correct the incorrect newline.

Behaviour: the REPL exits with an IndentationError.

Typing backspace works correctly when the cursor is on m.

The exit/crash does not happen in 3.14a7.

CPython versions tested on:

3.14, CPython main branch

Operating systems tested on:

macOS

Linked PRs

• gh-133541: Handle SyntaxError raised by the tokenizer on user input #133606
• [3.14] gh-133541: Handle SyntaxError raised by the tokenizer on user input (GH-133606) #133709