Fix package inclusion to accept any file's type

index.js

@@ -61,7 +61,10 @@ module.exports = class ServerlessPluginReducer {
 			const modulePathsSet = new Set(modulePaths);
 			await Promise.all(
 				normalizedIncludeModulePaths.map(includeModulePath => {
-					if (!includeModulePath.endsWith(".js")) return null;
+					if (!includeModulePath.endsWith(".js")) {
+						modulePathsSet.add(includeModulePath);
+						return null;
+					}
 					return getDependencies(servicePath, resolve(servicePath, includeModulePath), {
 						...options,
 						ServerlessError

test/index/success.js

@@ -79,5 +79,32 @@ test("Serverless Plugin Reducer: Success", t => {
 				}
 			);
 	});
+
+	t.test("Supports include with another type of files", t => {
+		packagePluginMock.getIncludes = () => ["some-lambda/some-extra-file"];
+		const onFinally = () => (packagePluginMock.getIncludes = () => []);
+		packagePluginMock
+			.resolveFilePathsFunction("some-lambda")
+			.then(result => {
+				t.deepEqual(
+					result.sort(),
+					[
+						"node_modules/some-dep/entry.js", "node_modules/some-dep/other.js",
+						"node_modules/some-dep/package.json", "some-lambda/foo.js",
+						"some-lambda/index.js", "some-lambda/some-extra-file"
+					].map(ensureOsSeparators)
+				);
+			})
+			.then(
+				() => {
+					onFinally();
+					t.end();
+				},
+				error => {
+					onFinally();
+					throw error;
+				}
+			);
+	});
 	t.end();
 });