Allow getJSON errors to be ignored

This change is mostly motivated to get a more stable CI build (we're building the Hugo site there, with Instagram and Twitter shortcodes sometimes failing).

Fixes #7866

hugolib/testhelpers_test.go

@@ -67,7 +67,7 @@ type sitesBuilder struct {
 
 	*qt.C
 
-	logger *loggers.Logger
+	logger loggers.Logger
 	rnd    *rand.Rand
 	dumper litter.Options
 
@@ -154,7 +154,7 @@ func (s *sitesBuilder) WithNothingAdded() *sitesBuilder {
 	return s
 }
 
-func (s *sitesBuilder) WithLogger(logger *loggers.Logger) *sitesBuilder {
+func (s *sitesBuilder) WithLogger(logger loggers.Logger) *sitesBuilder {
 	s.logger = logger
 	return s
 }