Handle config error in load config file.

tests/test_config.py

@@ -3,6 +3,7 @@ import pytest
 from tempfile import NamedTemporaryFile
 
 from sanic import Sanic
+from sanic.exceptions import PyFileError
 
 
 def test_load_from_object(app):
@@ -79,6 +80,16 @@ def test_load_from_missing_envvar(app):
                                 "could not be loaded.")
 
 
+def test_load_config_from_file_invalid_syntax(app):
+    config = b"VALUE = some value"
+    with NamedTemporaryFile() as config_file:
+        config_file.write(config)
+        config_file.seek(0)
+
+        with pytest.raises(PyFileError):
+            app.config.from_pyfile(config_file.name)
+
+
 def test_overwrite_exisiting_config(app):
     app.config.DEFAULT = 1