Improve handling of content decoding error messages

When dropping or PUTting non-UTF8 encoded textual content
the error messages were incomplete or not trapped.

Partially fixes #137. Additional changes in TiddlyWeb itself
provide better error messages and further discussion required
to determine if the server should be willing to decode different
types of content.

Author: cdent

tiddlywebplugins/tank/closet.py

@@ -90,7 +90,10 @@ def _regular_tiddler(environ, bag_name, input_file, target_name):
     content = input_file.file.read()
 
     tiddler = Tiddler(target_name, bag_name)
-    tiddler.text = content.decode('utf-8')
+    try:
+        tiddler.text = content.decode('utf-8')
+    except UnicodeError as exc:
+        raise HTTP400('tiddler content should be utf-8 encode: %s' % exc)
     tiddler.modifier = username
     tiddler.type = input_file.type
     store.put(tiddler)

tiddlywebplugins/tank/httperror.py

@@ -34,9 +34,17 @@ def send_error(environ, start_response, exc, allow=None):
     """
     Send the error mesage out via template.
     """
+
+    # Construct a message from the exception
+    if not hasattr(exc, 'args'):
+        exc.args = ('%s' % self,)
+    output = []
+    for arg in exc.args:
+        output.append('%s' % arg)
+
     error = {
         'status': exc.status,
-        'message': exc.message
+        'message': ' '.join(output)
     }
 
     headers = [('Content-type', 'text/html; charset=utf-8')]