In /logs/firmware/patool_extraction/rootfs.img_unblob_extracted/rootfs.img_extract/0-80367616.squashfs_v4_le_extract/usr/sbin/httpd-header-load line 20:

while IFS="=" read -r key_index header; do

                      ^-------^ SC2034 (warning): key_index appears unused. Verify use (or export if used externally).

In /logs/firmware/patool_extraction/rootfs.img_unblob_extracted/rootfs.img_extract/0-80367616.squashfs_v4_le_extract/usr/sbin/httpd-header-load line 25:

		echo $(header_generator $header_name "$header_value") >> $CUSTOMHEADER_CONF

                     ^-- SC2046 (warning): Quote this to prevent word splitting.

                     ^-- SC2005 (style): Useless echo? Instead of 'echo $(cmd)', just use 'cmd'.

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

Did you mean: 

		echo $(header_generator "$header_name" "$header_value") >> $CUSTOMHEADER_CONF

In /logs/firmware/patool_extraction/rootfs.img_unblob_extracted/rootfs.img_extract/0-80367616.squashfs_v4_le_extract/usr/sbin/httpd-header-load line 29:

echo $header_names

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

Did you mean: 

echo "$header_names"

For more information:

  https://www.shellcheck.net/wiki/SC2034 -- key_index appears unused. Verify ...

  https://www.shellcheck.net/wiki/SC2046 -- Quote this to prevent word splitt...

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