parse_file cannot return the expected error message.

[zong-zhe]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

// source code in 'parser/src/lib.rs'
pub fn parse_file(filename: &str, code: Option<String>) -> Result<ast::Module, String> {
    create_session_globals_then(move || {
        let src = if let Some(s) = code {
            s
        } else {
            // the read file failed error message can not return.
            std::fs::read_to_string(filename).unwrap()
        };
....
}

2. What did you expect to see? (Required)

// do not use unwrap() and return the error message.
std::fs::read_to_string(filename).unwrap()

3. What did you see instead (Required)

It will panic, instead of return error message.

4. What is your KusionStack components version? (Required)

kclvm version is 0.4.3; checksum: e07ed7af0d9bd1e86a3131714e4bd20c