Add nil check in ErrorResponse.Error method (#2971)

Fixes: #2970.

Author: rajatjindal

github/github.go

@@ -1017,9 +1017,17 @@ type ErrorBlock struct {
 }
 
 func (r *ErrorResponse) Error() string {
-	return fmt.Sprintf("%v %v: %d %v %+v",
-		r.Response.Request.Method, sanitizeURL(r.Response.Request.URL),
-		r.Response.StatusCode, r.Message, r.Errors)
+	if r.Response != nil && r.Response.Request != nil {
+		return fmt.Sprintf("%v %v: %d %v %+v",
+			r.Response.Request.Method, sanitizeURL(r.Response.Request.URL),
+			r.Response.StatusCode, r.Message, r.Errors)
+	}
+
+	if r.Response != nil {
+		return fmt.Sprintf("%d %v %+v", r.Response.StatusCode, r.Message, r.Errors)
+	}
+
+	return fmt.Sprintf("%v %+v", r.Message, r.Errors)
 }
 
 // Is returns whether the provided error equals this error.

github/github_test.go

@@ -2097,6 +2097,19 @@ func TestErrorResponse_Error(t *testing.T) {
 	if err.Error() == "" {
 		t.Errorf("Expected non-empty ErrorResponse.Error()")
 	}
+
+	//dont panic if request is nil
+	res = &http.Response{}
+	err = ErrorResponse{Message: "m", Response: res}
+	if err.Error() == "" {
+		t.Errorf("Expected non-empty ErrorResponse.Error()")
+	}
+
+	//dont panic if response is nil
+	err = ErrorResponse{Message: "m"}
+	if err.Error() == "" {
+		t.Errorf("Expected non-empty ErrorResponse.Error()")
+	}
 }
 
 func TestError_Error(t *testing.T) {