Prefer to wrap third party errors

[StevenACoffman]

Prior to #234 the method signature returned *gqlerror.Error which would return a typed nil, so that:

if err != nil {

would fail to detect errors.

Consumers of this library when the method signature returned *gqlerror.Error would frequently do this:

if gqlError != (*gqlerror.Error)(nil) {

Now that the method signature is to return the error interface the first one worked, and the second one no longer does (as it is now always untyped nil). 😞

Similarly, others consumers assume the error interface we return can always be asserted as (*gqlerror.Error) which is not entirely true, as we have some third-party errors which we return without wrapping.

This wraps a few of the most common calls to be able to be asserted as *gqlerror.Error without changing the return signature. However, there are a number of third-party errors we cannot easily wrap at the point of origination because it would cause cyclical dependencies.

I ran wrapcheck configured to ignore this package and found:

gqlparser/ast/decode.go:56:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:61:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:72:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:77:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:87:10: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:94:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:99:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:110:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:115:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:125:10: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:132:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:137:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:142:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:147:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:158:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:168:10: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:175:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:180:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:185:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:190:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:201:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:206:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/decode.go:211:12: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/path.go:42:10: error returned from external package is unwrapped: sig: func encoding/json.Unmarshal(data []byte, v any) error
gqlparser/ast/value.go:56:10: error returned from external package is unwrapped: sig: func strconv.ParseInt(s string, base int, bitSize int) (i int64, err error)
gqlparser/ast/value.go:58:10: error returned from external package is unwrapped: sig: func strconv.ParseFloat(s string, bitSize int) (float64, error)
gqlparser/ast/value.go:62:10: error returned from external package is unwrapped: sig: func strconv.ParseBool(str string) (bool, error)
gqlparser/validator/schema.go:17:15: error returned from external package is unwrapped: sig: func github.com/vektah/gqlparser/v2/parser.ParseSchemas(inputs ...*github.com/vektah/gqlparser/v2/ast.Source) (*github.com/vektah/gqlparser/v2/ast.SchemaDocument, error)

Signed-off-by: Steve Coffman steve@khanacademy.org

Describe your PR and link to any relevant issues.

I have:

• Added tests covering the bug / feature
• Updated any relevant documentation