src/process.c: In function ‘nixio__exec’:
src/process.c:76:26: error: comparison of constant ‘4’ with boolean expression is always true [-Werror=bool-compare]
if (!lua_type(L, -2) != LUA_TSTRING || !lua_isstring(L, -1)) {
^
src/process.c:76:26: error: logical not is only applied to the left hand side of comparison [-Werror=logical-not-parentheses]
Not sure what this is trying to do even