Hard Fault from np.array

[FoamyGuy]

Adafruit CircuitPython 10.0.3 on 2025-10-17; Adafruit MagTag with ESP32S2

With this reproducer code:

from displayio import Bitmap
import ulab.numpy as np

class IterableBitmap:
    def __init__(self, bitmap):
        self._bitmap = bitmap
        self.index = 0

    def __iter__(self):
        return self  # Object itself is the iterator

    def __next__(self):
        if self.index >= self._bitmap.width * self._bitmap.height:
            raise StopIteration
        item = self._bitmap[self.index]
        self.index += 1
        return item


source_bitmap = Bitmap(10,10, 10)
source_bitmap.fill(1)

iter_bmp = IterableBitmap(source_bitmap)

# un-commenting this iteration loop causes it not to hard fault
# for _ in iter_bmp:
#     print(_)

arr = np.array(iter_bmp, dtype=np.float)
print("after arr create")

while True:
    pass

The MagTag hard faults with "memory access or instruction error".

Interestingly if the print iteration loop before np.array() is un-commented then it no longer hard faults. But does not seem to create an array of the expected size either, but that is a separate, less severe issue.

Before I created this minimal reproducer I was trying to use similar code with an actual image and the MagTag hard crashed, but did not reset itself back into safe mode it just stayed crashed/disconnected from PC. I had to recover with manual safe mode access. This smaller reproducer seems to be able to get itself back into safe mode automatically though.