Replace some `unwrap` calls with `ok_or(Error::OperationFailed)`.

src/backends/appkit.rs

@@ -12,12 +12,12 @@ use crate::{Backend, BackendId, Error, Features, UtteranceId, Voice};
 pub(crate) struct AppKit(*mut Object, *mut Object);
 
 impl AppKit {
-    pub(crate) fn new() -> Self {
+    pub(crate) fn new() -> Result<Self, Error> {
         info!("Initializing AppKit backend");
         unsafe {
             let obj: *mut Object = msg_send![class!(NSSpeechSynthesizer), new];
-            let mut decl =
+            let mut decl = ClassDecl::new("MyNSSpeechSynthesizerDelegate", class!(NSObject))
-                ClassDecl::new("MyNSSpeechSynthesizerDelegate", class!(NSObject)).unwrap();
+                .ok_or(Error::OperationFailed)?;
             decl.add_ivar::<id>("synth");
             decl.add_ivar::<id>("strings");
 
@@ -81,11 +81,17 @@ impl AppKit {
 
             let delegate_class = decl.register();
             let delegate_obj: *mut Object = msg_send![delegate_class, new];
-            delegate_obj.as_mut().unwrap().set_ivar("synth", obj);
+            delegate_obj
+                .as_mut()
+                .ok_or(Error::OperationFailed)?
+                .set_ivar("synth", obj);
             let strings: id = msg_send![class!(NSMutableArray), new];
-            delegate_obj.as_mut().unwrap().set_ivar("strings", strings);
+            delegate_obj
+                .as_mut()
+                .ok_or(Error::OperationFailed)?
+                .set_ivar("strings", strings);
             let _: Object = msg_send![obj, setDelegate: delegate_obj];
-            AppKit(obj, delegate_obj)
+            Ok(AppKit(obj, delegate_obj))
         }
     }
 }

src/backends/av_foundation.rs

@@ -29,9 +29,10 @@ lazy_static! {
 }
 
 impl AvFoundation {
-    pub(crate) fn new() -> Self {
+    pub(crate) fn new() -> Result<Self, Error> {
         info!("Initializing AVFoundation backend");
-        let mut decl = ClassDecl::new("MyNSSpeechSynthesizerDelegate", class!(NSObject)).unwrap();
+        let mut decl = ClassDecl::new("MyNSSpeechSynthesizerDelegate", class!(NSObject))
+            .ok_or(Error::OperationFailed)?;
         decl.add_ivar::<u64>("backend_id");
 
         extern "C" fn speech_synthesizer_did_start_speech_utterance(
@@ -149,7 +150,7 @@ impl AvFoundation {
             }
         };
         *backend_id += 1;
-        rv
+        Ok(rv)
     }
 }
 

src/lib.rs

@@ -293,12 +293,12 @@ impl Tts {
                 Ok(Tts(Arc::new(RwLock::new(Box::new(tts)))))
             }
             #[cfg(target_os = "macos")]
-            Backends::AppKit => Ok(Tts(Arc::new(RwLock::new(
+            Backends::AppKit => Ok(Tts(Arc::new(RwLock::new(Box::new(
-                Box::new(backends::AppKit::new()),
+                backends::AppKit::new()?
-            )))),
+            ))))),
             #[cfg(any(target_os = "macos", target_os = "ios"))]
             Backends::AvFoundation => Ok(Tts(Arc::new(RwLock::new(Box::new(
-                backends::AvFoundation::new(),
+                backends::AvFoundation::new()?,
             ))))),
             #[cfg(target_os = "android")]
             Backends::Android => {