Crash for nested params during GET

If the params config was nested and the request method was a GET request
we would get a crash during parsing the parameters.

If the param map is not [string,string] it will be ignored now.

endpoint/endpoint.go

@@ -153,9 +153,16 @@ func (ep *EndpointConfig) GetRequestParams() map[string]string {
 		return make(map[string]string)
 	}
 	paramsMap := make(map[string]string)
-	children, _ := ep.json.S("data").ChildrenMap()
+	children, err := ep.json.S("data").ChildrenMap()
+	if err != nil {
+		return paramsMap
+	}
 	for key, child := range children {
-		paramsMap[key] = expandFakes(config.ExpandString(child.Data().(string)))
+		childData, ok := child.Data().(string)
+		if ok {
+			paramsMap[key] = expandFakes(config.ExpandString(childData))
+		}
+
 	}
 	return paramsMap
 }

request/request_test.go

@@ -19,3 +19,29 @@ func TestMain(m *testing.M) {
 	testhelper.Teardown()
 	os.Exit(retCode)
 }
+
+func TestBadGetdata(t *testing.T) {
+	ts := testhelper.RunTestServer(`
+				{
+					"inner": {
+						"value": "1234567890"
+					}
+				}
+			`)
+	defer ts.Close()
+	epConfig := testhelper.EndpointConfig(`
+		{
+			"url": "%s",
+			"method": "GET",
+			"data": {
+				"outer": [
+					{ "inner": "test" }
+				]
+			}
+		}
+	`, ts.URL)
+	_, err := Do(epConfig)
+	if err != nil {
+		t.Fatalf("Error making request: %s", err)
+	}
+}