feat(rpc/errorToObject): extract errorToObject function

src/rpc/errorToObject.js

@@ -0,0 +1,20 @@
+// @flow
+export default function errorToObject(error: ?Error): void | Object {
+  const errorObj = {};
+
+  if (error === undefined) {
+    return undefined;
+  } else if (error === null) {
+    return undefined;
+  }
+
+  Object.getOwnPropertyNames(error).forEach(key => {
+    if (/.*__old\d+/.test(key)) {
+      return;
+    }
+
+    errorObj[key] = (error: any)[key];
+  });
+
+  return errorObj;
+}

src/rpc/errorToObject.test.js

@@ -0,0 +1,26 @@
+// @flow
+import test from 'ava';
+import EError from 'eerror';
+import errorToObject from './errorToObject';
+
+test('call with undefined', t => {
+  t.is(errorToObject(undefined), undefined);
+});
+
+test('call with null', t => {
+  t.is(errorToObject(null), undefined);
+});
+
+test('call with eerror', t => {
+  const error = new EError('My awesome error').combine({
+    name: 'AwesomeError',
+    foo: { bar: 42 },
+  });
+
+  t.deepEqual(errorToObject(error), {
+    name: 'AwesomeError',
+    foo: { bar: 42 },
+    message: 'My awesome error',
+    stack: error.stack,
+  });
+});