bug: potential runtime crashes from unwrap/expect usage

[Ishita-190]

Files:

• apps/mofa-asr/src/screen/mod.rs,
• node-hub/dora-funasr-nano-mlx/src/main.rs
• mofa-dora-bridge/src/parser.rs
• node-hub/dora-gpt-sovits-mlx/src/ssml.rs

Several runtime and UI code paths rely on unwrap(), expect(), or other panic-based error handling. These constructs terminate execution when encountering unexpected Err or None values.

Current Behavior:

• Startup logic unwraps optional engine state, which may terminate execution if initialization fails.
• UI code uses expect("... mutex poisoned"), causing additional panics if a mutex becomes poisoned after a prior failure.
• Parser and SSML logic unwrap parsing results that may depend on external or user-provided input.
• Some tests use raw unwrap() calls that produce less informative failures.

Expected Behavior:

• Runtime code should propagate errors using Result instead of panicking.
• Missing configuration or state should produce logged, recoverable errors.
• UI paths should recover safely from poisoned mutexes.
• Parsing failures should return structured errors rather than terminating execution.

Proposed Changes:

1. In node-hub/dora-funasr-nano-mlx/src/main.rs:

Current:

let engine = engine.as_mut().unwrap();

Proposed:

let engine = match engine.as_mut() {
    Some(e) => e,
    None => {
        log::error!("Engine unexpectedly missing after attempted initialization");
        send_log(&mut node, "ERROR", "Engine not available")?;
        continue;
    }
};

2. In apps/mofa-asr/src/screen/mod.rs:

Current:

let mut guard = controller.lock().expect("ChatController mutex poisoned");

Proposed:

let mut guard = match controller.lock() {
    Ok(g) => g,
    Err(poisoned) => {
        log::warn!("ChatController mutex poisoned; recovering inner state");
        poisoned.into_inner()
    }
};

3. In mofa-dora-bridge/src/parser.rs:

Current:

let parsed = DataflowParser::parse_string(yaml, PathBuf::from("test.yml")).unwrap();

Proposed:

let parsed = DataflowParser::parse_string(yaml, PathBuf::from("test.yml"))
    .expect("DataflowParser failed to parse a valid test YAML; check parser changes");

4. In node-hub/dora-gpt-sovits-mlx/src/ssml.rs:

Current:

let result = parse_ssml("<speak>hello world</speak>").unwrap();

Proposed:

let result = parse_ssml("<speak>hello world</speak>")
    .expect("parse_ssml should parse simple <speak> content");

Would like to work on a PR for this if the maintainers approve