global_settings.py: add error handling for /Users/Shared write

resources/global_settings.py

@@ -21,15 +21,17 @@ class global_settings:
         plistlib.dump({"Developed by Dortania": True,}, Path(self.global_settings_plist).open("wb"))
 
     def read_property(self, property_name):
-        plist = plistlib.load(Path(self.global_settings_plist).open("rb"))
-        if property_name in plist:
-            return plist[property_name]
+        if Path(self.global_settings_plist).exists():
+            plist = plistlib.load(Path(self.global_settings_plist).open("rb"))
+            if property_name in plist:
+                return plist[property_name]
         return None
 
     def write_property(self, property_name, property_value):
-        plist = plistlib.load(Path(self.global_settings_plist).open("rb"))
-        plist[property_name] = property_value
-        plistlib.dump(plist, Path(self.global_settings_plist).open("wb"))
+        if Path(self.global_settings_plist).exists():
+            plist = plistlib.load(Path(self.global_settings_plist).open("rb"))
+            plist[property_name] = property_value
+            plistlib.dump(plist, Path(self.global_settings_plist).open("wb"))
 
 
     def convert_defaults_to_global_settings(self):
@@ -41,7 +43,11 @@ class global_settings:
             # merge defaults with global settings
             global_settings_plist = plistlib.load(Path(self.global_settings_plist).open("rb"))
             global_settings_plist.update(defaults_plist)
-            plistlib.dump(global_settings_plist, Path(self.global_settings_plist).open("wb"))
+            try:
+                plistlib.dump(global_settings_plist, Path(self.global_settings_plist).open("wb"))
+            except PermissionError:
+                print("- Permission error: Unable to write to global settings file")
+                return
 
             # delete defaults plist
             Path(defaults_path).unlink()