[BUG] Rust panic on unrecognized --dvblang value: Language::from_str().expect() in copy_to_rust()

[NexionisJake]

Summary

Passing any unrecognized language code via --dvblang causes an unconditional
Rust panic that crashes the entire CCExtractor process with no user-facing error
message.

Location

src/rust/src/common.rs — copy_to_rust(), line ~427

Code

Language::from_str(&c_char_to_string(...)).expect("Invalid language")

Language::from_str() uses strum's EnumString derive. For any string not
in the Language enum (e.g. --dvblang xyz), it returns Err. The .expect()
call converts this into an unconditional panic, crashing the process instead of
printing a helpful CLI error.

Reproduction

ccextractor input.ts --dvblang xyz
# thread 'main' panicked at 'Invalid language', src/rust/src/common.rs:427

Expected Behaviour

CCExtractor should print a diagnostic like:
"Unknown language code 'xyz' — using default" and continue, or exit with a
clean error message.

Suggested Fix

Replace:

Language::from_str(&lang_str).expect("Invalid language")

With either:

// Option A — silent fallback
Language::from_str(&lang_str).unwrap_or_default()

// Option B — user-facing error (preferred)
Language::from_str(&lang_str).unwrap_or_else(|_| {
    eprintln!("Warning: unknown language code '{}', using default", lang_str);
    Language::default()
})

Environment

• Affects all platforms
• Reproducible with any unrecognized ISO 639 code passed to --dvblang

[ananyaaa66]

Is anyone working in this?