fix(github): Clear label on empty notifications

Fixes #278

include/drawtypes/label.hpp

@@ -60,6 +60,7 @@ namespace drawtypes {
     string get() const;
     operator bool();
     label_t clone();
+    void clear();
     void reset_tokens();
     bool has_token(const string& token);
     void replace_token(const string& token, string replacement);

src/drawtypes/label.cpp

@@ -24,6 +24,10 @@ namespace drawtypes {
         m_margin, m_maxlen, m_ellipsis, move(tokens));
   }
 
+  void label::clear() {
+    m_tokenized.clear();
+  }
+
   void label::reset_tokens() {
     m_tokenized = m_text;
   }

src/modules/github.cpp

@@ -1,5 +1,7 @@
-#include "modules/github.hpp"
+#include <cassert>
+
 #include "drawtypes/label.hpp"
+#include "modules/github.hpp"
 
 #include "modules/meta/base.inl"
 
@@ -23,6 +25,8 @@ namespace modules {
       m_label = load_optional_label(m_conf, name(), TAG_LABEL, "Notifications: %notifications%");
       m_label->replace_token("%notifications%", m_empty_notifications ? "0" : "");
     }
+
+    assert(static_cast<bool>(m_label));
   }
 
   /**
@@ -50,9 +54,11 @@ namespace modules {
       notifications++;
     }
 
-    if (m_label) {
+    if (notifications || m_empty_notifications) {
       m_label->reset_tokens();
-      m_label->replace_token("%notifications%", notifications || m_empty_notifications ? to_string(notifications) : "");
+      m_label->replace_token("%notifications%", to_string(notifications));
+    } else {
+      m_label->clear();
     }
 
     return true;