Unhelpful error messages for Rust

[petervdonovan]

The error message "aborting due to previous error; 4 warnings emitted" is unhelpful. Maybe it should be suppressed, or shown only if there are no other error messages.

Perhaps the real problem is "use of a blacklisted/placeholder name baz [foo.rs:61:17]," but that message does not show up consistently (i.e., on the same file, whether it appears seems to be nondeterministic). The user has to go to View > Problems in order to see the other messages. This is particularly confusing because when you use the "Build and Run" command, the program compiles and runs with no issues.

This can be reproduced (unreliably) by opening lingua-franca/test/Rust/src/TimeState.lf in VS Code.

[lhstrh]

Tagging @oowekyala as he might be able to help with this?