[fud2] improve error message for parser errors (#2258)

It does what it says on the tin. The error messages for the parser won't
be good, but they are better than rust panics and I think become
functional enough.

One interesting thing to note is I chose to print full paths when
referencing files. This is because the directory of scripts is often not
where `fud2` was run from and pretty unrelated to that dir.

fud2/fud-core/src/exec/driver.rs

@@ -439,7 +439,10 @@ impl DriverBuilder {
     }
 
     /// Load any plugin scripts specified in the configuration file.
-    pub fn load_plugins(mut self, config_data: &figment::Figment) -> Self {
+    pub fn load_plugins(
+        mut self,
+        config_data: &figment::Figment,
+    ) -> anyhow::Result<Self> {
         // pull out things from self that we need
         let plugin_dir = self.scripts_dir.take();
         let plugin_files = self.script_files.take();
@@ -455,7 +458,7 @@ impl DriverBuilder {
                     .filter_map(|dir_entry| dir_entry.map(|p| p.path()).ok())
                     // filter out paths that don't have `.rhai` extension
                     .filter(|p| p.extension() == Some(OsStr::new("rhai"))),
-            );
+            )?;
         }
 
         // add static plugins (where string is included in binary)
@@ -467,10 +470,10 @@ impl DriverBuilder {
         if let Ok(plugins) =
             config_data.extract_inner::<Vec<std::path::PathBuf>>("plugins")
         {
-            runner.add_files(plugins.into_iter());
+            runner.add_files(plugins.into_iter())?;
         }
 
-        runner.run()
+        Ok(runner.run())
     }
 
     pub fn build(self) -> Driver {

fud2/fud-core/src/script/plugin.rs

@@ -462,14 +462,24 @@ impl ScriptRunner {
     pub fn add_files(
         &mut self,
         files: impl Iterator<Item = PathBuf>,
-    ) -> &mut Self {
+    ) -> anyhow::Result<&mut Self> {
         for f in files {
-            let ast = self.engine.compile_file(f.clone()).unwrap();
+            let res = self.engine.compile_file(f.clone());
+            let ast = match res {
+                Err(e) => {
+                    return Err(anyhow::format_err!(
+                        "{} in {}",
+                        e,
+                        f.to_str().unwrap()
+                    ))
+                }
+                Ok(ast) => ast,
+            };
             let functions =
                 self.resolver.as_mut().unwrap().register_path(f, ast);
             self.rhai_functions = self.rhai_functions.merge(&functions);
         }
-        self
+        Ok(self)
     }
 
     pub fn add_static_files(

fud2/src/main.rs

@@ -41,7 +41,7 @@ fn main() -> anyhow::Result<()> {
 
     #[cfg(feature = "migrate_to_scripts")]
     {
-        bld = bld.load_plugins(&config);
+        bld = bld.load_plugins(&config)?;
     }
 
     let driver = bld.build();

fud2/tests/tests.rs

@@ -22,7 +22,7 @@ fn test_driver() -> Driver {
     let mut bld = DriverBuilder::new("fud2-plugins");
     let config = figment::Figment::new();
     bld.scripts_dir(manifest_dir_macros::directory_path!("scripts"));
-    bld.load_plugins(&config).build()
+    bld.load_plugins(&config).unwrap().build()
 }
 
 fn driver_from_path_with_config(
@@ -36,7 +36,7 @@ fn driver_from_path_with_config(
         path
     );
     bld.scripts_dir(&path);
-    bld.load_plugins(&config).build()
+    bld.load_plugins(&config).unwrap().build()
 }
 
 fn driver_from_path(path: &str) -> Driver {