Fix unicode problems in web plugin

Added Exception to the web plugin to catch non latin-1 characters and change them to ascii chars.
Added Description to the changelog file

beetsplug/web/__init__.py

@@ -24,6 +24,7 @@ import flask
 from flask import g
 from werkzeug.routing import BaseConverter, PathConverter
 import os
+from unidecode import unidecode
 import json
 import base64
 
@@ -224,12 +225,12 @@ def item_file(item_id):
         item_path = util.syspath(item.path)
     else:
         item_path = util.py3_path(item.path)
+    try:
+        os.path.basename(util.py3_path(item.path)).encode("latin-1", "strict") #Imitate http.server behaviour
+        response = flask.send_file(item_path,as_attachment=True)
+    except UnicodeEncodeError:
+        response = flask.send_file(item_path,as_attachment=True, attachment_filename=unidecode(os.path.basename(util.py3_path(item.path))))
 
-    response = flask.send_file(
-        item_path,
-        as_attachment=True,
-        attachment_filename=os.path.basename(util.py3_path(item.path)),
-    )
     response.headers['Content-Length'] = os.path.getsize(item_path)
     return response
 

docs/changelog.rst

@@ -75,6 +75,10 @@ Fixes:
   album art would not work and throw an exception. It now works as expected.
   Additionally, the server will now return a 404 response when the album id
   is unknown, instead of a 500 response and a thrown exception. :bug:`2823`
+* :doc:`/plugins/web`: In a python 3 enviroment, the server would throw an 
+  exception if non latin-1 characters where in the File name.
+  It now checks if non latin-1 characters are in the filename and changes 
+  them to ascii-characters in that case :bug:`2815`
 
 For developers: