feat(package): ignore private JS packages (#975)

`private: true` in `package.json` files means that the package is not supposed to be published to npm, which makes the `version` field meaningless, so we should probably ignore it to not clutter the prompt too much.

src/modules/package.rs

@@ -41,6 +41,11 @@ fn extract_cargo_version(file_contents: &str) -> Option<String> {
 
 fn extract_package_version(file_contents: &str) -> Option<String> {
     let package_json: json::Value = json::from_str(file_contents).ok()?;
+
+    if package_json.get("private").and_then(json::Value::as_bool) == Some(true) {
+        return None;
+    }
+
     let raw_version = package_json.get("version")?.as_str()?;
     if raw_version == "null" {
         return None;
@@ -163,7 +168,10 @@ mod tests {
             extract_package_version(&package_with_version),
             expected_version
         );
+    }
 
+    #[test]
+    fn test_extract_package_version_without_version() {
         let package_without_version = json::json!({
             "name": "spacefish"
         })
@@ -176,6 +184,49 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_extract_package_version_with_null_version() {
+        let package_with_null_version = json::json!({
+            "name": "spacefish",
+            "version": null
+        })
+        .to_string();
+
+        let expected_version = None;
+        assert_eq!(
+            extract_package_version(&package_with_null_version),
+            expected_version
+        );
+    }
+
+    #[test]
+    fn test_extract_package_version_with_null_string_version() {
+        let package_with_null_string_version = json::json!({
+            "name": "spacefish",
+            "version": "null"
+        })
+        .to_string();
+
+        let expected_version = None;
+        assert_eq!(
+            extract_package_version(&package_with_null_string_version),
+            expected_version
+        );
+    }
+
+    #[test]
+    fn test_extract_private_package_version() {
+        let private_package = json::json!({
+            "name": "spacefish",
+            "version": "0.1.0",
+            "private": true
+        })
+        .to_string();
+
+        let expected_version = None;
+        assert_eq!(extract_package_version(&private_package), expected_version);
+    }
+
     #[test]
     fn test_extract_poetry_version() {
         let poetry_with_version = toml::toml! {