feat: Make mod resource scripts optional

With splitting DMF and DML, there is now more than one case where this
is needed, so it may well be made proper now.
The template still defines them, and, as with VT2 most creators will
probably stick with it, but they do have the option to make a non-DMF
mod now.

crates/dtmm/src/engine.rs

@@ -156,15 +156,31 @@ fn build_mod_data_lua(state: Arc<State>) -> String {
         lua.push_str(mod_info.get_id());
 
         lua.push_str("\",\n        run = function()\n");
-        lua.push_str("            return new_mod(\"");
+
-        lua.push_str(mod_info.get_name());
+        let resources = mod_info.get_resources();
+        if resources.get_data().is_some() || resources.get_localization().is_some() {
+            lua.push_str("            new_mod(\"");
+            lua.push_str(mod_info.get_id());
             lua.push_str("\", {\n                init = \"");
-        lua.push_str(mod_info.get_resources().get_init());
+            lua.push_str(resources.get_init());
+
+            if let Some(data) = resources.get_data() {
                 lua.push_str("\",\n                data = \"");
-        lua.push_str(mod_info.get_resources().get_data());
+                lua.push_str(data);
+            }
+
+            if let Some(localization) = resources.get_localization() {
                 lua.push_str("\",\n                localization = \"");
-        lua.push_str(mod_info.get_resources().get_localization());
+                lua.push_str(localization);
+            }
+
             lua.push_str("\",\n            })\n");
+        } else {
+            lua.push_str("            return dofile(\"");
+            lua.push_str(resources.get_init());
+            lua.push_str("\")");
+        }
+
         lua.push_str("        end,\n        packages = [\n");
 
         for pkg_info in mod_info.get_packages() {

crates/dtmm/src/state.rs

@@ -62,8 +62,8 @@ impl PackageInfo {
 #[derive(Clone, Data, Debug)]
 pub(crate) struct ModResourceInfo {
     init: String,
-    data: String,
+    data: Option<String>,
-    localization: String,
+    localization: Option<String>,
 }
 
 impl ModResourceInfo {
@@ -71,12 +71,12 @@ impl ModResourceInfo {
         &self.init
     }
 
-    pub(crate) fn get_data(&self) -> &String {
+    pub(crate) fn get_data(&self) -> Option<&String> {
-        &self.data
+        self.data.as_ref()
     }
 
-    pub(crate) fn get_localization(&self) -> &String {
+    pub(crate) fn get_localization(&self) -> Option<&String> {
-        &self.localization
+        self.localization.as_ref()
     }
 }
 

crates/dtmt/src/cmd/build.rs

@@ -72,9 +72,12 @@ async fn find_project_config(dir: Option<PathBuf>) -> Result<ModConfig> {
     };
 
     let mut buf = String::new();
-    file.read_to_string(&mut buf).await?;
+    file.read_to_string(&mut buf)
+        .await
+        .wrap_err("invalid UTF-8")?;
 
-    let mut cfg: ModConfig = serde_sjson::from_str(&buf)?;
+    let mut cfg: ModConfig =
+        serde_sjson::from_str(&buf).wrap_err("failed to deserialize mod config")?;
     cfg.dir = path;
     Ok(cfg)
 }

lib/sdk/src/lib.rs

@@ -13,8 +13,10 @@ pub use context::Context;
 #[derive(Clone, Debug, Default, serde::Deserialize)]
 pub struct ModConfigResources {
     pub init: String,
-    pub data: String,
+    #[serde(default)]
-    pub localization: String,
+    pub data: Option<String>,
+    #[serde(default)]
+    pub localization: Option<String>,
 }
 
 #[derive(Clone, Debug, Default, serde::Deserialize)]