indent-error-flow reports a false positive

[mgechev]

Describe the bug

indent-error-flow gives false positive for:

func h(f func() bool, x int) string {
	if err == author.ErrCourseNotFound {
		return
	} else if err == author.ErrCourseAccess {
		// side effect
	} else if err == author.AnotherError {
		return "okay"
	} else {
		// side effect
	}
}

To Reproduce
Steps to reproduce the behavior:

1. I updated revive go get -u github.com/mgechev/revive
2. I run the rule indent-error-flow
3. I got a warning if block ends with a return statement, so drop this else and outdent its block

Expected behavior

Should not get a warning in the case above because of the else if statements.

[mgechev]

@chavacava let me know if you want to take this one.

[chavacava]

Hi, please take a look to the corresponding pull request.