fixes nil reference exception if localization text is empty, fixes #207…

… (#208)

v2/goi18n/merge_command.go

@@ -125,12 +125,16 @@ func merge(messageFiles map[string][]byte, sourceLanguageTag language.Tag, outdi
 		}
 		templates := map[string]*i18n.MessageTemplate{}
 		for _, m := range mf.Messages {
-			templates[m.ID] = i18n.NewMessageTemplate(m)
+			template := i18n.NewMessageTemplate(m)
+			if template == nil {
+				continue
+			}
+			templates[m.ID] = template
 		}
 		if mf.Tag == sourceLanguageTag {
 			for _, template := range templates {
 				if sourceMessageTemplates[template.ID] != nil {
-					return nil, fmt.Errorf("multiple source translations for id %s", template.ID)
+					return nil, fmt.Errorf("multiple source translations for id %q", template.ID)
 				}
 				template.Hash = hash(template)
 				sourceMessageTemplates[template.ID] = template

v2/goi18n/merge_command_test.go

@@ -35,6 +35,20 @@ func TestMerge(t *testing.T) {
 				"active.en-US.toml": []byte("1HelloMessage = \"Hello\"\n"),
 			},
 		},
+		{
+			name:           "single identity, one localization text missing",
+			sourceLanguage: language.AmericanEnglish,
+			inFiles: map[string][]byte{
+				"one.en-US.toml": []byte(`
+1HelloMessage = ""
+Body = "Finally some text!"
+`),
+			},
+			outFiles: map[string][]byte{
+				"active.en-US.toml": []byte(`Body = "Finally some text!"
+`),
+			},
+		},
 		{
 			name:           "plural identity",
 			sourceLanguage: language.AmericanEnglish,
@@ -52,6 +66,24 @@ other = "{{.Count}} unread emails"
 description = "Message that tells the user how many unread emails they have"
 one = "{{.Count}} unread email"
 other = "{{.Count}} unread emails"
+`),
+			},
+		},
+		{
+			name:           "plural identity, missing localization text",
+			sourceLanguage: language.AmericanEnglish,
+			inFiles: map[string][]byte{
+				"active.en-US.toml": []byte(`
+Body = "Some text!"
+
+[MissingTranslation]
+description = "I wonder what it was?!"
+one = ""
+other = ""
+`),
+			},
+			outFiles: map[string][]byte{
+				"active.en-US.toml": expectFile(`Body = "Some text!"
 `),
 			},
 		},