In /logs/firmware/patool_extraction/rootfs.img_unblob_extracted/rootfs.img_extract/0-50593792.squashfs_v4_le_extract/usr/lib/conf-migrate/upgrade-run.d/upnp line 7:

. /lib/rcscripts/sh/files.sh

  ^------------------------^ SC1091 (info): Not following: /lib/rcscripts/sh/files.sh was not specified as input (see shellcheck -x).

In /logs/firmware/patool_extraction/rootfs.img_unblob_extracted/rootfs.img_extract/0-50593792.squashfs_v4_le_extract/usr/lib/conf-migrate/upgrade-run.d/upnp line 19:

if [ -f $1$old_upnp_conf_file ] && [ -r $1$old_upnp_conf_file ]; then

        ^-- SC2086 (info): Double quote to prevent globbing and word splitting.

                                        ^-- SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean: 

if [ -f "$1"$old_upnp_conf_file ] && [ -r "$1"$old_upnp_conf_file ]; then

In /logs/firmware/patool_extraction/rootfs.img_unblob_extracted/rootfs.img_extract/0-50593792.squashfs_v4_le_extract/usr/lib/conf-migrate/upgrade-run.d/upnp line 20:

  . $1$old_upnp_conf_file || error "Failed to source file: $1$old_upnp_conf_file"

    ^-------------------^ SC1090 (warning): ShellCheck can't follow non-constant source. Use a directive to specify location.

    ^-- SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean: 

  . "$1"$old_upnp_conf_file || error "Failed to source file: $1$old_upnp_conf_file"

In /logs/firmware/patool_extraction/rootfs.img_unblob_extracted/rootfs.img_extract/0-50593792.squashfs_v4_le_extract/usr/lib/conf-migrate/upgrade-run.d/upnp line 32:

elif [ -f $1$upnp_conf ] && [ -r $1$upnp_conf ]; then

          ^-- SC2086 (info): Double quote to prevent globbing and word splitting.

                                 ^-- SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean: 

elif [ -f "$1"$upnp_conf ] && [ -r "$1"$upnp_conf ]; then

In /logs/firmware/patool_extraction/rootfs.img_unblob_extracted/rootfs.img_extract/0-50593792.squashfs_v4_le_extract/usr/lib/conf-migrate/upgrade-run.d/upnp line 33:

  cp -f $1$upnp_conf $upnp_conf ||

        ^-- SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean: 

  cp -f "$1"$upnp_conf $upnp_conf ||

For more information:

  https://www.shellcheck.net/wiki/SC1090 -- ShellCheck can't follow non-const...

  https://www.shellcheck.net/wiki/SC1091 -- Not following: /lib/rcscripts/sh/...

  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...