Fix empty uploads in forms (#520)

emmett/forms.py

@@ -384,8 +384,8 @@ async def _process(self, **kwargs):
             #: handle uploads
             for field in filter(lambda f: f.type == "upload", self.writable_fields):
                 upload = self.files[field.name]
-                del_field = field.name + "__del"
-                if not upload.filename:
+                if not upload:
+                    del_field = field.name + "__del"
                     if self.input_params.get(del_field, False):
                         self.params[field.name] = self.table[field.name].default or ""
                         # TODO: do we want to physically delete file?

pyproject.toml

@@ -35,7 +35,7 @@ classifiers = [
 
 dependencies = [
     "click>=6.0",
-    "emmett-core[granian,rapidjson]~=1.0.2",
+    "emmett-core[granian,rapidjson]~=1.0.4",
     "emmett-pydal==17.3.1",
     "pendulum~=3.0.0",
     "pyyaml~=6.0",