fix: declare ES module in package.json

In bundler mode, generate the package.json with "type": "module" and use the
"main" attribute instead of the "module" attribute.

This change makes the built ES module palatable to node in
--experimental-wasm-modules mode as well as to webpack as illustrated in
https://github.com/webpack/webpack/pull/14313

src/manifest/mod.rs

@@ -699,6 +699,7 @@ impl CrateData {
 
         NpmPackage::ESModulesPackage(ESModulesPackage {
             name: data.name,
+            type_: "module".into(),
             collaborators: pkg.authors.clone(),
             description: self.manifest.package.description.clone(),
             version: pkg.version.to_string(),
@@ -713,7 +714,7 @@ impl CrateData {
                     url: repo_url,
                 }),
             files: data.files,
-            module: data.main,
+            main: data.main,
             homepage: data.homepage,
             types: data.dts_file,
             side_effects: false,
@@ -729,6 +730,7 @@ impl CrateData {
 
         NpmPackage::ESModulesPackage(ESModulesPackage {
             name: data.name,
+            type_: "module".into(),
             collaborators: pkg.authors.clone(),
             description: self.manifest.package.description.clone(),
             version: pkg.version.to_string(),
@@ -743,7 +745,7 @@ impl CrateData {
                     url: repo_url,
                 }),
             files: data.files,
-            module: data.main,
+            main: data.main,
             homepage: data.homepage,
             types: data.dts_file,
             side_effects: false,

src/manifest/npm/esmodules.rs

@@ -3,6 +3,8 @@ use manifest::npm::repository::Repository;
 #[derive(Serialize)]
 pub struct ESModulesPackage {
     pub name: String,
+    #[serde(rename = "type")]
+    pub type_: String,
     #[serde(skip_serializing_if = "Vec::is_empty")]
     pub collaborators: Vec<String>,
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -14,7 +16,7 @@ pub struct ESModulesPackage {
     pub repository: Option<Repository>,
     #[serde(skip_serializing_if = "Vec::is_empty")]
     pub files: Vec<String>,
-    pub module: String,
+    pub main: String,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub homepage: Option<String>,
     #[serde(skip_serializing_if = "Option::is_none")]