Exit with 1 on Err

Created by: cmichi

You can provoke this by e.g. applying this patch to ink/examples/dns/Cargo.toml:

 [lib]
-name = "dns"
+name = "d ns"

and then

cargo run -- contract build --manifest-path ../ink/examples/dns/Cargo.toml 
echo $?

After the merge we should move the ink-ci-v0.8.0 tag ahead to this commit.

This is another reason why some of the stages in the ink! CI succeed even though cargo-contract fails.