I get an Error Testing my site under ios 10 mobile safari. The problem is that i cannot debug it because the code is minified and the error message does not give me any hint at all.
Is threre anyway to debug the unminified build?

Hey Artur,
if you want to have an unminified build + sourcemaps you have to visit the site while running gatsby develop. You can read here how to do it:
https://github.com/gatsbyjs/gatsby/issues/5801
There's also the --no-uglify flag, gatsby build --no-uglify should do a full build and skip the minification step.
@m-allanson thanks i already discovered and used it. it seems the uglification of gatsby caused error in safari 10. do you know if one can tweek the uglifcation settings like this?
`
uglify: {
uglifyOptions: {
mangle: { safari10: true }
}
}
Fixed in #10536