Nicely handle errors loading default extensions

import logging

import traceback

from contextlib import contextmanager

@contextmanager

def handle_extension_error(extension_name):

    """'gracefully' log an error if an extension fails to load."""

    try:

        yield

    except Exception as e:

        logging.error(

            f"Exception loading builtin extension picamera_autocalibrate: \n{traceback.format_exc()}"

        )

with handle_extension_error("autofocus"):

    from .autofocus import autofocus_extension_v2

with handle_extension_error("scan"):

    from .scan import scan_extension_v2

with handle_extension_error("zip builder"):

    from .zip_builder import zip_extension_v2

with handle_extension_error("autostorage"):

    from .autostorage import autostorage_extension_v2

with handle_extension_error("camera stage mapping"):

    from .camera_stage_mapping import csm_extension

# "Gracefully" handle cases where picamera cannot be imported (eg test server)

try:

with handle_extension_error("lens shading calibration"):

    from .picamera_autocalibrate import lst_extension_v2

except Exception as e:

    logging.error(

        f"Exception loading builtin extension picamera_autocalibrate: \n{traceback.format_exc()}"

    )

#FIXME: this oughtn't stay in the production version...

with handle_extension_error("custom element example"):

    from ..example_extensions.custom_element import customelement_extension_v2