Handle invalid ChangeEvent APIErrorObject response (#479)

client.go

@@ -83,14 +83,37 @@ type APIErrorObject struct {
 	Errors  []string `json:"errors,omitempty"`
 }
 
-// fallbackAPIErrorObject is a shim to solve this issue:
-// https://github.com/PagerDuty/go-pagerduty/issues/339
-//
-// TODO: remove when PagerDuty engineering confirms bugfix to the REST API
-type fallbackAPIErrorObject struct {
-	Code    int    `json:"code,omitempty"`
-	Message string `json:"message,omitempty"`
-	Errors  string `json:"errors,omitempty"`
+func unmarshalApiErrorObject(data []byte) (APIErrorObject, error) {
+	var aeo APIErrorObject
+	err := json.Unmarshal(data, &aeo)
+	if err == nil {
+		return aeo, nil
+	}
+	if _, ok := err.(*json.UnmarshalTypeError); !ok {
+		return aeo, nil
+	}
+	// See - https://github.com/PagerDuty/go-pagerduty/issues/339
+	// TODO: remove when PagerDuty engineering confirms bugfix to the REST API
+	var fallback1 struct {
+		Code    int    `json:"code,omitempty"`
+		Message string `json:"message,omitempty"`
+		Errors  string `json:"errors,omitempty"`
+	}
+	if json.Unmarshal(data, &fallback1) == nil {
+		aeo.Code = fallback1.Code
+		aeo.Message = fallback1.Message
+		aeo.Errors = []string{fallback1.Errors}
+		return aeo, nil
+	}
+	// See - https://github.com/PagerDuty/go-pagerduty/issues/478
+	var fallback2 []string
+	if json.Unmarshal(data, &fallback2) == nil {
+		aeo.Message = "none"
+		aeo.Errors = fallback2
+		return aeo, nil
+	}
+	// still failed, so return the original error
+	return aeo, err
 }
 
 // NullAPIErrorObject is a wrapper around the APIErrorObject type. If the Valid
@@ -111,28 +134,9 @@ var _ json.Unmarshaler = (*NullAPIErrorObject)(nil) // assert that it satisfies
 
 // UnmarshalJSON satisfies encoding/json.Unmarshaler
 func (n *NullAPIErrorObject) UnmarshalJSON(data []byte) error {
-	var aeo APIErrorObject
-
-	err := json.Unmarshal(data, &aeo)
+	aeo, err := unmarshalApiErrorObject(data)
 	if err != nil {
-		terr, ok := err.(*json.UnmarshalTypeError)
-		if !ok {
-			return err
-		}
-
-		//
-		// see https://github.com/PagerDuty/go-pagerduty/issues/339
-		//
-		var faeo fallbackAPIErrorObject
-
-		if err := json.Unmarshal(data, &faeo); err != nil {
-			// still failed, so return the original error
-			return terr
-		}
-
-		aeo.Code = faeo.Code
-		aeo.Message = faeo.Message
-		aeo.Errors = []string{faeo.Errors}
+		return err
 	}
 
 	n.ErrorObject = aeo

client_test.go

@@ -136,6 +136,11 @@ func TestAPIError_Error(t *testing.T) {
 				input: `{"error":{"code": 420, "message": "Enhance Your Calm", "errors":["No Seriously, Enhance Your Calm", "Slow Your Roll", "No, really..."]}}`,
 				want:  "HTTP response failed with status code 429, message: Enhance Your Calm (code: 420): No Seriously, Enhance Your Calm (and 2 more errors...)",
 			},
+			{
+				name:  "issue_478",
+				input: `{"error":["links should have at most 50 item(s)"]}`,
+				want:  "HTTP response failed with status code 429, message: none (code: 0): links should have at most 50 item(s)",
+			},
 		}
 
 		for _, tt := range tests {