Fix vtx frequency backward compatibility

Author: klutvott123

src/SCRIPTS/BF/PAGES/vtx.lua

@@ -35,6 +35,8 @@ end
 
 if apiVersion >= 1.037 then
     fields[#fields + 1] = { t = "Frequency", x = x, y = inc.y(lineSpacing), sp = x + sp, min = 5000, max = 5999,                   vals = { 6 }, upd = function(self) self.handleFreqValUpdate(self) end }
+elseif apiVersion >= 1.036 then
+    fields[#fields + 1] = { t = "Frequency", x = x, y = inc.y(lineSpacing), sp = x + sp, min = 5000, max = 5999, ro = true }
 end
 
 -- Vals                     Fields

src/SCRIPTS/BF/ui.lua

@@ -342,7 +342,7 @@ local function run_ui(event)
             elseif event == EVT_VIRTUAL_ENTER then
                 if Page then
                     local f = Page.fields[currentField]
-                    if Page.values and Page.values[f.vals[#f.vals]] and not f.ro then
+                    if Page.values and f.vals and Page.values[f.vals[#f.vals]] and not f.ro then
                         pageState = pageStatus.editing
                     end
                 end