segfault with improper use of super()

Port, board and/or hardware

unix, coverage build

MicroPython version

MicroPython v1.26.0-preview.387.ge4e97f5aa7.dirty on 2025-07-20; linux [GCC 12.2.0] version

Reproduction

Run the following code:

import framebuf

class FB(framebuf.FrameBuffer):
    def __init__(self, n):
        self = n
        super().__init__(bytearray(2 * n * n), n, n, framebuf.RGB565)

fb = FB(n=3)

Expected behaviour

super() should not segfault.

Observed behaviour

crash in native_base_init_wrapper

Program received signal SIGSEGV, Segmentation fault.
0x00005555556120c7 in native_base_init_wrapper (n_args=5, args=0x7fffffffd6c0, 
    kw_args=0x7fffffffd510) at ../../py/objtype.c:91
91	    instance_count_native_bases(self->base.type, &native_base);
(gdb) p self
$1 = (mp_obj_instance_t *) 0x7

Additional Information

This is a minimized version of a script produced by fuzzing micropython.

Code of Conduct

Yes, I agree

Reproduce the example in a Unix coverage build, then inspect native_base_init_wrapper in ../../py/objtype.c around line 91, where the crash reports self as an invalid pointer. Verify the behavior after the issue is addressed by rerunning the example and confirming that improper use of super() no longer segfaults.