Fix goreportcard issues (#271)

* Fixed misspell

* Fixed ineffassign

`user` and `password` always got overwritten
`orderedVals` was initialized with an empty array but always got overwritten by either `sortByLines()` or `sortAlphabetical`
`err` was assigned a `nil` value that was either overwritten or unused anyways

* Fix comment for DeletePath

The comment assumed the method was named Delete, i guess a rename happened at some point

* Update doc_test.go

marshal.go

@@ -546,8 +546,8 @@ func (d *Decoder) valueFromTree(mtype reflect.Type, tval *Tree) (reflect.Value,
 
 				if !found && opts.defaultValue != "" {
 					mvalf := mval.Field(i)
-					var val interface{} = nil
-					var err error = nil
+					var val interface{}
+					var err error
 					switch mvalf.Kind() {
 					case reflect.Bool:
 						val, err = strconv.ParseBool(opts.defaultValue)