Added check to ensure we are in lighttable view prior to callling darktable.register_lib. If darktable was invoked in single image (darkroom) mode, then an event handler is registered to detect the change from darkroom mode to lighttable mode so that we can then call darktable.register_lib.

contrib/geoToolbox.lua

@@ -40,6 +40,12 @@ local function _(msgid)
     return gettext.dgettext("geoToolbox", msgid)
 end
 
+
+local gT = {}
+gT.module_installed = false
+gT.event_registered = false
+
+
 -- <GUI>
 local labelDistance = dt.new_widget("label")
 labelDistance.label = _("Distance:")
@@ -572,6 +578,22 @@ local function altitude_profile()
 
 end
 
+local function install_module()
+  if not gT.module_installed then
+    dt.register_lib(
+      "geoToolbox",        -- Module name
+      "geo toolbox",       -- name
+      true,                -- expandable
+      false,               -- resetable
+      {[dt.gui.views.lighttable] = {"DT_UI_CONTAINER_PANEL_RIGHT_CENTER", 100}},   -- containers
+      gT.widget,
+      nil,-- view_enter
+      nil -- view_leave
+    )
+    gT.module_installed = true
+  end
+end
+
 
 local separator = dt.new_widget("separator"){}
 local separator2 = dt.new_widget("separator"){}
@@ -579,13 +601,7 @@ local separator3 = dt.new_widget("separator"){}
 local separator4 = dt.new_widget("separator"){}
 local separator5 = dt.new_widget("separator"){}
 
-dt.register_lib(
-  "geoToolbox",        -- Module name
-  "geo toolbox",       -- name
-  true,                -- expandable
-  false,               -- resetable
-  {[dt.gui.views.lighttable] = {"DT_UI_CONTAINER_PANEL_RIGHT_CENTER", 100}},   -- containers
-  dt.new_widget("box")
+gT.widget = dt.new_widget("box")
   {
     orientation = "vertical",
     dt.new_widget("button")
@@ -664,10 +680,24 @@ dt.register_lib(
       clicked_callback = altitude_profile
     },
     labelDistance
-  },
-  nil,-- view_enter
-  nil -- view_leave
-)
+  }
+
+
+if dt.gui.current_view().name == "lighttable" then
+  install_module()
+else
+  if not gT.event_registered then
+    dt.register_event(
+      "view-changed",
+      function(event, old_view, new_view)
+        if new_view.name == "lighttable" and old_view.name == "darkroom" then
+          install_module()
+         end
+      end
+    )
+    gT.event_registered = true
+  end
+end
 
 -- Preferences
 dt.preferences.register("geoToolbox",