[[FEAT]] Drop repeated info on toString

Author: Javier Mendiara Cañardo

lib/index.js

@@ -50,15 +50,13 @@ function toObject(error, withStack) {
 }
 
 function toString(error, withStack) {
-  var ret = [formatError(error)]
-      .concat(getCauses(error).map(formatMessage))
-      .join(': ');
-
   if (withStack && error instanceof Error) {
-    ret += '\n' + getFullErrorStack(error);
+    return getFullErrorStack(error);
+  } else {
+    return [formatError(error)]
+        .concat(getCauses(error).map(formatMessage))
+        .join(': ')
   }
-
-  return ret;
 }
 
 /*

test/toString.spec.js

@@ -28,9 +28,7 @@ describe('toString', function() {
     var err = new Error('foo');
     var obj = serializeError(err).toString(true);
 
-    expect(obj).to.be.eql('Error: foo' +
-        '\n' + err.stack
-    );
+    expect(obj).to.be.eql(err.stack);
   });
 
   describe('with cause', function() {
@@ -65,8 +63,7 @@ describe('toString', function() {
       err.cause = sandbox.stub().returns(err1);
       var obj = serializeError(err).toString(true);
 
-      expect(obj).to.be.eql('Error: foo: bar: baz' +
-        '\n' + err.stack +
+      expect(obj).to.be.eql(err.stack +
         '\nCaused by: ' + err1.stack +
         '\nCaused by: ' + err2
       );