[oden] Catch and render script errors, stop crashing

This is kinda nice actually

oden-js/src/lib.rs

@@ -41,7 +41,7 @@ pub enum Error {
     ConversionError(String),
     #[error("an error occurred calling a rust function: {0}")]
     RustFunctionError(String),
-    #[error("an exception was thrown during evaluation: {1}\nStack: {2}")]
+    #[error("an exception was thrown during evaluation: {1}\nStack:\n{2}")]
     Exception(Value, String, String),
     #[error("out of memory")]
     OutOfMemory,

src/script.rs

@@ -15,7 +15,7 @@ mod input;
 mod io;
 mod time;
 
-use graphics::GraphicsCommand;
+use graphics::{ClearCommand, GraphicsCommand, PrintCommand};
 
 mod typescript;
 use typescript::transpile_to_javascript;
@@ -66,6 +66,8 @@ pub struct ScriptContext {
 
     time: time::TimeAPI,
     input: input::InputAPI,
+
+    error_lines: Vec<String>,
 }
 
 impl ScriptContext {
@@ -115,6 +117,8 @@ impl ScriptContext {
 
             time,
             input,
+
+            error_lines: Vec::new(),
         })
     }
 
@@ -123,15 +127,17 @@ impl ScriptContext {
     pub fn suspend(&self) -> Option<Vec<u8>> {
         let _span = span!("script suspend");
         if !self.suspend.is_undefined() {
-            let suspend_state = self
-                .suspend
-                .call(&self.context, &[&self.state])
-                .expect("Exception in suspend");
-            Some(
-                suspend_state
-                    .serialize(&self.context)
-                    .expect("Unable to serialize state"),
-            )
+            match self.suspend.call(&self.context, &[&self.state]) {
+                Ok(suspend_state) => Some(
+                    suspend_state
+                        .serialize(&self.context)
+                        .expect("Unable to serialize state"),
+                ),
+                Err(e) => {
+                    eprintln!("WARNING: Error during suspend, state will not be saved: {e}");
+                    None
+                }
+            }
         } else {
             None
         }
@@ -151,6 +157,10 @@ impl ScriptContext {
     pub fn update(&mut self) {
         let _span = span!("script update");
 
+        if self.error_lines.len() > 0 {
+            return; // Don't bother, nothing.
+        }
+
         // Do we update the frame time before of after async completion?
         // Hmmmmm.
         self.time.set_frame_time(Instant::now());
@@ -159,37 +169,69 @@ impl ScriptContext {
         // promise completions.
         {
             let _span = span!("process jobs");
-            self.context
-                .process_all_jobs()
-                .expect("Error processing async jobs");
+            self.handle_result(self.context.process_all_jobs());
         }
 
         // Now run the update function.
-        {
+        if self.error_lines.len() == 0 {
             let _span = span!("javascript update");
             let old_state = &self.state;
-            self.state = self
-                .update
-                .call(&self.context, &[old_state])
-                .expect("Exception in update");
+            self.state = match self.update.call(&self.context, &[old_state]) {
+                Ok(v) => v,
+                Err(e) => {
+                    self.handle_error(e);
+                    self.context.null()
+                }
+            }
         }
     }
 
     pub fn render(&mut self) -> Vec<graphics::GraphicsCommand> {
         let _span = span!("script render");
+        if self.error_lines.len() > 0 {
+            // TODO: Use font 0 for a fallback.
+            let mut commands = vec![
+                GraphicsCommand::Clear(ClearCommand {
+                    color: [0.0, 0.0, 1.0, 1.0],
+                }),
+                GraphicsCommand::Print(PrintCommand {
+                    text: "FATAL SCRIPT ERROR".to_owned(),
+                    pos: [6.0, 6.0],
+                }),
+            ];
 
-        self.draw
-            .call(&self.context, &[&self.state])
-            .expect("Exception in draw");
-        self.gfx.end_frame();
-
-        let mut commands = Vec::new();
-        loop {
-            match self.gfx_receive.recv().unwrap() {
-                GraphicsCommand::EndFrame => break,
-                other => commands.push(other),
+            let mut y = 20.0;
+            for line in &self.error_lines {
+                commands.push(GraphicsCommand::Print(PrintCommand {
+                    text: line.clone(),
+                    pos: [6.0, y],
+                }));
+                y += 8.0;
             }
+
+            commands
+        } else {
+            self.handle_result(self.draw.call(&self.context, &[&self.state]));
+            self.gfx.end_frame();
+
+            let mut commands = Vec::new();
+            loop {
+                match self.gfx_receive.recv().unwrap() {
+                    GraphicsCommand::EndFrame => break,
+                    other => commands.push(other),
+                }
+            }
+            commands
         }
-        commands
+    }
+
+    fn handle_result<T>(&mut self, result: Result<T>) {
+        if let Err(e) = result {
+            self.handle_error(e);
+        }
+    }
+
+    fn handle_error(&mut self, error: oden_js::Error) {
+        self.error_lines = error.to_string().lines().map(|l| l.to_owned()).collect();
     }
 }