server: better error handling for connection closing

server/main.py

@@ -2,6 +2,7 @@
 
 import asyncio
 import json, random, re, math, time, traceback
+from websockets.exceptions import ConnectionClosed, ConnectionClosedOK
 from websockets.asyncio.server import serve
 
 from db import Database
@@ -48,6 +49,12 @@ def serverError(msg,**kwargs) -> str:
 sessionUsers = {}
 sessionCreatedAccount = []
 
+def forgetSession(sid):
+    if sid in sessionUsers:
+        del sessionUsers[sid]
+    if sid in sessionCreatedAccount:
+        sessionCreatedAccount.remove(sid)
+
 async def handleCommand(ws,cmd):
     global sessionUsers
     print(f"recieved command: {cmd} (from {id(ws)})")
@@ -59,6 +66,8 @@ async def handleCommand(ws,cmd):
     match cmd["type"]:
         case "ping":
             return await ws.send(response("Pong!"))
+
+        # accounts
         case "createuser":
             if uid != None:
                 return await ws.send(clientError("You are already logged in."))
@@ -163,9 +172,19 @@ async def serveClient(ws):
             except Exception as e:
                 traceback.print_exception(e)
                 await ws.send(serverError(f"Cannot process command ({cmd["type"]})"))
+        except json.decoder.JSONDecodeError:
+            await ws.send(serverError("Cannot process JSON."))
+        except ConnectionClosedOK:
+            print(f"connection {id(ws)} has closed")
+            forgetSession(id(ws))
+            break
+        except ConnectionClosed as e:
+            print(f"connection {id(ws)} has closed with a non-OK exit code:")
+            traceback.print_exception(e)
+            break
         except Exception as e:
             traceback.print_exception(e)
-            await ws.send(serverError("Cannot process JSON."))
+            await ws.send(serverError("Cannot parse command."))
 
 async def main():
     async with serve(serveClient, "", 30341) as server: