fix for mitmproxy#4852 (mitmproxy#4857)

* fix for mitmproxy#4852

* changelog

Author: rbdixon

CHANGELOG.md

@@ -11,6 +11,7 @@
 * Add `client_replay_concurrency` option, which allows more than one client replay request to be in-flight at a time. (@rbdixon)
 * New content view which handles gRPC/protobuf. Allows to apply custom definitions to visualize different field decodings.
   Includes example addon which applies custom definitions for selected gRPC traffic (@mame82)
+* Fix a crash caused when editing string option (#4852, @rbdixon)
 
 ## 28 September 2021: mitmproxy 7.0.4
 

mitmproxy/tools/console/options.py

@@ -181,7 +181,8 @@ def keypress(self, size, key):
                 foc, idx = self.get_focus()
                 v = self.walker.get_edit_text()
                 try:
-                    d = self.master.options.parse_setval(foc.opt, v)
+                    current = getattr(self.master.options, foc.opt.name)
+                    d = self.master.options.parse_setval(foc.opt, v, current)
                     self.master.options.update(**{foc.opt.name: d})
                 except exceptions.OptionsError as v:
                     signals.status_message.send(message=str(v))