Doesn't check for return

[jaekwon]

Preprocessor doesn't check whether all code branch paths return in functions that have a return value.
This causes unexpected behavior during runtime, in my case I got:
interface conversion: gno.Stmt is nil, not *gno.AssignStmt.

TODO: make preprocessor ensure all branch paths return when necessary.
Alternatively, use the go compiler for type-checking.

[moul]

Alternatively, use the go compiler for type-checking

Sounds like a very smart quick-win to me

From a shell, I would not use go build but go fmt -e which will be a way faster and only focused on syntax checking

The source code is here: https://cs.opensource.google/go/go/+/refs/tags/go1.18:src/cmd/gofmt/gofmt.go;l=225

[jaekwon]

related https://github.com/gnolang/bounties#10-use-go-typechecker

[moul]

@jaekwon I plan to update #119 to automatically run unit tests against the official examples/gno.land/* gno files

If you have any pieces of code that you think relevant enough to be hardcoded in the gno2go unit tests because you worry they happen in production, feel free to update my PR or share here some code snippets, and I can handle the rest