Fix exception division by zero

src/cutecoin/core/community.py

@@ -165,7 +165,10 @@ class Community(QObject):
         """
         blocks = self.bma_access.get(self, qtbma.blockchain.UD)['result']['blocks']
         if len(blocks) > 0:
-            block_number = blocks[len(blocks)-(1+x)]
+            index = len(blocks)-(1+x)
+            if index < 0:
+                index = 0
+            block_number = blocks[index]
             block = self.bma_access.get(self, qtbma.blockchain.Block,
                                  req_args={'number': block_number})
             return block

src/cutecoin/gui/informations_tab.py

@@ -150,7 +150,7 @@ class InformationsTabWidget(QWidget, Ui_InformationsTabWidget):
                     localized_mass_minus_1_per_member,
                     self.tr('Monetary Mass per member M(t-1)/N(t) in'),
                     self.get_referential_diff_name(),
-                    float(0) if block_ud['membersCount'] == 0 else
+                    float(0) if block_ud['membersCount'] == 0 or block_ud_minus_1['monetaryMass'] == 0 else
                     block_ud['dividend'] / (block_ud_minus_1['monetaryMass'] / block_ud['membersCount']),
 
                     params['dt'] / 86400,