upb: fix Ruby bug which allowed map.delete(key) on a frozen map

Also clean up some compiler warnings about exiting from non-void functions without returning a value.

PiperOrigin-RevId: 595185251

ruby/ext/google/protobuf_c/map.c

@@ -444,7 +444,7 @@ static VALUE Map_delete(VALUE _self, VALUE key) {
       Convert_RubyToUpb(key, "", Map_keyinfo(self), NULL);
   upb_MessageValue val_upb;
 
-  if (upb_Map_Delete(self->map, key_upb, &val_upb)) {
+  if (upb_Map_Delete(Map_GetMutable(_self), key_upb, &val_upb)) {
     return Convert_UpbToRuby(val_upb, self->value_type_info, self->arena);
   } else {
     return Qnil;

ruby/ext/google/protobuf_c/shared_message.c

@@ -29,12 +29,12 @@ uint64_t shared_Message_Hash(const upb_Message* msg, const upb_MessageDef* m,
     uint64_t ret = _upb_Hash(data, size, seed);
     upb_Arena_Free(arena);
     return ret;
-  } else {
+  }
+
   upb_Arena_Free(arena);
   upb_Status_SetErrorMessage(status, "Error calculating hash");
   return 0;
 }
-}
 
 // Support function for Message_Equal
 bool shared_Message_Equal(const upb_Message* m1, const upb_Message* m2,
@@ -59,8 +59,9 @@ bool shared_Message_Equal(const upb_Message* m1, const upb_Message* m2,
     bool ret = (size1 == size2) && (memcmp(data1, data2, size1) == 0);
     upb_Arena_Free(arena_tmp);
     return ret;
-  } else {
+  }
+
   upb_Arena_Free(arena_tmp);
   upb_Status_SetErrorMessage(status, "Error comparing messages");
-  }
+  return 0;
 }