gen_handles script fails with pwmleds handle

[nordicjm]

Describe the bug
The updates to the gen_handles scripts which adds support for graphviz output seems to fail in specific circumstances, a project for example has this contents in the dev_handles.c file:

/* 1 : /soc/clock@40000000:
 */
const device_handle_t __aligned(2) __attribute__((__section__(".__device_handles_pass2")))
__devicehdl_DT_N_S_soc_S_clock_40000000[] = { DEVICE_HANDLE_SEP, DEVICE_HANDLE_SEP, DEVICE_HANDLE_ENDS };

/* 2 : /soc/gpio@50000300:
 */
const device_handle_t __aligned(2) __attribute__((__section__(".__device_handles_pass2")))
__devicehdl_DT_N_S_soc_S_gpio_50000300[] = { DEVICE_HANDLE_SEP, DEVICE_HANDLE_SEP, DEVICE_HANDLE_ENDS };

/* 3 : /soc/gpio@50000000:
 */
const device_handle_t __aligned(2) __attribute__((__section__(".__device_handles_pass2")))
__devicehdl_DT_N_S_soc_S_gpio_50000000[] = { DEVICE_HANDLE_SEP, DEVICE_HANDLE_SEP, DEVICE_HANDLE_ENDS };

/* 4 : /soc/uart@40028000:
 */
const device_handle_t __aligned(2) __attribute__((__section__(".__device_handles_pass2")))
__devicehdl_DT_N_S_soc_S_uart_40028000[] = { DEVICE_HANDLE_SEP, DEVICE_HANDLE_SEP, DEVICE_HANDLE_ENDS };

/* 5 : /soc/uart@40002000:
 */
const device_handle_t __aligned(2) __attribute__((__section__(".__device_handles_pass2")))
__devicehdl_DT_N_S_soc_S_uart_40002000[] = { DEVICE_HANDLE_SEP, DEVICE_HANDLE_SEP, DEVICE_HANDLE_ENDS };

/* 6 : /soc/pwm@4002d000:
 */
const device_handle_t __aligned(2) __attribute__((__section__(".__device_handles_pass2")))
__devicehdl_DT_N_S_soc_S_pwm_4002d000[] = { DEVICE_HANDLE_SEP, DEVICE_HANDLE_SEP, DEVICE_HANDLE_ENDS };

/* 7 : /soc/pwm@40022000:
 */
const device_handle_t __aligned(2) __attribute__((__section__(".__device_handles_pass2")))
__devicehdl_DT_N_S_soc_S_pwm_40022000[] = { DEVICE_HANDLE_SEP, DEVICE_HANDLE_SEP, DEVICE_HANDLE_ENDS };

/* 8 : /soc/pwm@40021000:
 */
const device_handle_t __aligned(2) __attribute__((__section__(".__device_handles_pass2")))
__devicehdl_DT_N_S_soc_S_pwm_40021000[] = { DEVICE_HANDLE_SEP, DEVICE_HANDLE_SEP, DEVICE_HANDLE_ENDS };

/* 9 : /soc/pwm@4001c000:
 */
const device_handle_t __aligned(2) __attribute__((__section__(".__device_handles_pass2")))
__devicehdl_DT_N_S_soc_S_pwm_4001c000[] = { DEVICE_HANDLE_SEP, DEVICE_HANDLE_SEP, DEVICE_HANDLE_ENDS };

/* 10 : /pwmleds:
 */
const device_handle_t __aligned(2) __attribute__((__section__(".__device_handles_pass2")))
__devicehdl_DT_N_S_pwmleds[] = { DEVICE_HANDLE_SEP, DEVICE_HANDLE_SEP, DEVICE_HANDLE_ENDS };

The script fails on the last part due to label on line 271 of scripts/build/elf_parser.py being none:

cd nrf/samples/caf/_AA/zephyr && /usr/bin/python3.10 zephyr/scripts/build/gen_handles.py --output-source dev_handles.c --output-graphviz dev_graph.dot --num-dynamic-devices 0 --kernel nrf/samples/caf/_AA/zephyr/zephyr_pre0.elf --zephyr-base zephyr --start-symbol __device_start
Traceback (most recent call last):
  File "zephyr/scripts/build/gen_handles.py", line 141, in <module>
    main()
  File "zephyr/scripts/build/gen_handles.py", line 124, in main
    dot = parsed_elf.device_dependency_graph('Device dependency graph', args.kernel)
  File "zephyr/scripts/build/elf_parser.py", line 272, in device_dependency_graph
    text = '{:s}\\nOrdinal: {:d} | Handle: {:d}\\n{:s}'.format(
TypeError: unsupported format string passed to NoneType.__format__
ninja: build stopped: subcommand failed.

A workaround is to check if the label type is none, but I don't think that is the correct solution. Reverting commit 2994247 allows the script to work

To Reproduce
Requires use of the nRF connect SDK to get the features required to exhibit this issue, but getting nrfconnect/sdk-nrf#8327 with west and then trying to build nrf/samples/caf for the nrf52840dk_nrf52840 board shows the issue

Expected behavior
No error or script failure

Impact
Showstopper

Environment (please complete the following information):

• OS: Linux
• Toolchain: Zephyr SDK 0.15.0-rc1
• Commit SHA or Version used: For zephyr, using commit 71ef669

[gmarull]

This has been fixed 7007451

[nordicjm]

This has been fixed 7007451

Wonderful! Thanks