Refactor: Avoid using nested try-except block

As nesting try-excepts makes readability worst.

python/pre.py

@@ -7,37 +7,40 @@ import js
 import base64
 from pyodide.http import pyfetch
 
-# prepare pssh
-pssh = PSSH(pssh)
+def blobsToDevice(cID, pKey):
+    return Device(client_id=cID, private_key=pKey, type_=DeviceTypes['ANDROID'], security_level=3, flags=None)
 
-# load device
+async def loadCdm():
+    # Looking for device.wvd
     try:
         wvd = await (await pyfetch("device.wvd")).bytes()
-    device = Device.loads(wvd)
-except Exception:
+        return Cdm.from_device(Device.loads(wvd))
+    except:
+        pass
+
+    # Looking for device_client_id_blob + device_private_key
     try:
-        print("device.wvd not found! looking for device_client_id_blob and device_private_key...")
         cID=await (await pyfetch("device_client_id_blob")).bytes()
         pKey=await (await pyfetch("device_private_key")).bytes()
+        return Cdm.from_device(blobsToDevice(cID, pKey))
+    except:
+        pass
 
-    except Exception:
+    # Looking for client_id.bin + private_key.pem
     try:
-            print("device_client_id_blob and device_private_key not found! looking for client_id.bin and private_key.pem...")
         cID=await (await pyfetch("client_id.bin")).bytes()
         pKey=await (await pyfetch("private_key.pem")).bytes()
-
+        return Cdm.from_device(blobsToDevice(cID, pKey))
     except Exception as e:
         js.document.getElementById('result').value="n0suchd3v1c3f113:r3adth3fuck1ngma2ua1\n\n[MPD?]\nhttps://github.com/FoxRefire/wvg?tab=readme-ov-file#instalation"
         raise Exception(e)
 
-    device = Device(client_id=cID,
-                private_key=pKey,
-                type_=DeviceTypes['ANDROID'],
-                security_level=3,
-                flags=None)
+
+# prepare pssh
+pssh = PSSH(pssh)
 
 # load cdm
-cdm = Cdm.from_device(device)
+cdm = await loadCdm()
 
 # open cdm session
 session_id = cdm.open()