all: simplify nested complexity and if blocks ending with a return statement (#21854)

Changes:

    Simplify nested complexity
    If an if blocks ends with a return statement then remove the else nesting.

Most of the changes has also been reported in golint https://goreportcard.com/report/github.com/ethereum/go-ethereum#golint

trie/committer.go

@@ -267,6 +267,5 @@ func estimateSize(n node) int {
 		return 1 + len(n)
 	default:
 		panic(fmt.Sprintf("node type %T", n))
-
 	}
 }