How can I add header every location if query exist Nginx - nginx

Question

I have two url
http://localhost/?shop=test
http://localhost/login?shop=test
first url is working. But second url coming 404 nginx page. how can I fix this problem. I want to every location come header if exist shop query
server {
listen 8081 default_server;
listen [::]:8081 default_server;
server_name _;
location / {
if ( $arg_shop ) {
add_header Content-Security-Policy "frame-ancestors https://$arg_shop";
}
root /home;
index index.html;
include /etc/nginx/mime.types;
try_files $uri $uri/ /index.html?$query_string;
}
}

Answer 1

The problem with using if inside a location, is that it doesn't work the way you expect.
You can use a map to define the value of the add_header directive. If the argument is missing or empty, the header will not be added.
For example:
map $arg_shop $csp {
"" "";
default "frame-ancestors https://$arg_shop";
}
server {
...
add_header Content-Security-Policy $csp;
location / {
...
}
}

Answer 2

I fixed like that
server {
listen 8081 default_server;
listen [::]:8081 default_server;
server_name _;
location / {
error_page 404 = #error_page;
if ( $arg_shop ) {
add_header "Content-Security-Policy" "frame-ancestors https://$arg_shop";
}
root /home;
index index.html;
include /etc/nginx/mime.types;
try_files $uri $uri/ /index.html?$query_string;
}
location #error_page {
add_header "Content-Security-Policy" "frame-ancestors https://$arg_shop";
root /home;
index index.html;
include /etc/nginx/mime.types;
try_files $uri $uri/ /index.html?$query_string;
}
}