Return nil instead of nil value

[marcelloh]

Describe the bug
It's not really a bug, but more of a "thing to do, when coding in Go"

In the generated code, there is a lot of:

		if templ_7745c5c3_Err != nil {
			return templ_7745c5c3_Err
		}
		return templ_7745c5c3_Err

but it is more idiomatic to return just nil, like this:

		if templ_7745c5c3_Err != nil {
			return templ_7745c5c3_Err
		}
		return nil

[a-h]

I'd take a PR for that.