Refactor away rightward drift in main

[clux]

Using

1. let else instead of big indent + else at the bottom
2. returning error early
3. continue early

then 2 more minor tweaks: crd iterations common var + use Vec<&str> for less to_string gunk

[clux]

highlighting what caused de-indents. no other changes in that main loop in generate apart from the two pointed out causing double deindent. although this is easier to review if you check the "ignore indent" thing.

[Dav1dde]

Nice