actually fix

gui.py

@@ -509,12 +509,12 @@ class DocumentWindow(QMainWindow):
 
             self.window.chordTableView.populate(self.doc.chordList)
             # remove the chord if any of the blocks have it attached
+            if self.currentSection is not None:
                 for s in self.doc.sectionList:
                         for b in s.blockList:
                             if b.chord:
                                 if b.chord.name == oldName:
                                     b.chord = None
-            if self.currentSection.blockList is not None:
                 self.window.blockTableView.populate(self.currentSection.blockList)
             self.clearChordLineEdits()
             self.updateChordDict()