Wrong error handling in resource.Environment() method

[YuriiBarninets]

Description

There is a misprint within resource.Environment() method that leads to the following log entry:

2021/04/27 17:32:32 < nil >

The condition has to be if err != nil

Steps To Reproduce

1. Create SDK Tracer Provider with TracerProviderOption that will configure Resource, e.g.

opts []trace.TracerProviderOption
opts = append(opts , trace.WithResource(resource.NewWithAttributes(semconv.ServiceNameKey.String("Test service"))))
tp := sdktrace.NewTracerProvider(opts ...)

Expected behavior

There should not be 2021/04/27 17:32:32 < nil > log entry.