More code improvements

Updates the deprecated typing imports + more general fixes.

game/helper_functions/renpy_overrides_ren.py

@@ -15,10 +15,12 @@ def convert_field_override(self, value, conversion):
         return value
 
     if not conversion:
-        raise ValueError("Conversion specifier can't be empty.")
+        msg = "Conversion specifier can't be empty."
+        raise ValueError(msg)
 
     if set(conversion) - set("rstqulci!"):
-        raise ValueError("Unknown symbols in conversion specifier, this must use only the \"rstqulci\".")
+        msg = 'Unknown symbols in conversion specifier, this must use only the "rstqulci".'
+        raise ValueError(msg)
 
     if "r" in conversion:
         value = repr(value)
@@ -41,7 +43,8 @@ def convert_field_override(self, value, conversion):
         try:
             value = self.vformat(value, (), kwargs)
         except RuntimeError as exc: # PY3 RecursionError
-            raise ValueError("Substitution {!r} refers to itself in a loop.".format(value)) from exc
+            msg = "Substitution {!r} refers to itself in a loop.".format(value)
+            raise ValueError(msg) from exc
 
     if "q" in conversion:
         value = value.replace("{", "{{")