Merge pull request #531 from will-moore/handle_missing_pixel_size_z_s…

…ymbol

Fix missing pixel_size_z_symbol in Figure_To_Pdf.py

omero_figure/scripts/omero/figure_scripts/Figure_To_Pdf.py

@@ -1247,6 +1247,7 @@ def draw_labels(self, panel, page):
                         z_symbol = panel.get('pixel_size_z_symbol')
                         if pixel_size_z is None:
                             pixel_size_z = 0
+                        if z_symbol is None:
                             z_symbol = "\xB5m"
 
                         if ("z_projection" in panel.keys()