in about:config
default extensions.webextensions.default-content-security-policy.v3 is script-src 'self'; upgrade-insecure-requests;
change it to script-src 'self' 'unsafe-eval' http://localhost:8063 http://localhost:8064;
extensions.webextensions.base-content-security-policy.v3
default is
script-src 'self' 'wasm-unsafe-eval';
change it to script-src 'self' 'unsafe-eval' 'wasm-unsafe-eval' http://localhost:8063 http://localhost:8064; script-src-elem 'self' http://localhost:8063 http://localhost:8064;