error for missing channel private key

lbry/error/README.md

@@ -52,6 +52,7 @@ Code | Name | Message
 405 | ChannelKeyNotFound | Channel signing key not found.
 406 | ChannelKeyInvalid | Channel signing key is out of date. -- For example, channel was updated but you don't have the updated key.
 407 | DataDownload | Failed to download blob. *generic*
+408 | PrivateKeyNotFound | Couldn't find private key for {key} '{value}'.
 410 | Resolve | Failed to resolve '{url}'.
 411 | ResolveTimeout | Failed to resolve '{url}' within the timeout.
 411 | ResolveCensored | Resolve of '{url}' was censored by channel with claim id '{censor_id}'.

lbry/error/__init__.py

@@ -207,6 +207,14 @@ class DataDownloadError(WalletError):
         super().__init__("Failed to download blob. *generic*")
 
 
+class PrivateKeyNotFoundError(WalletError):
+
+    def __init__(self, key, value):
+        self.key = key
+        self.value = value
+        super().__init__(f"Couldn't find private key for {key} '{value}'.")
+
+
 class ResolveError(WalletError):
 
     def __init__(self, url):

lbry/extras/daemon/daemon.py

@@ -38,7 +38,7 @@ from lbry.dht.peer import make_kademlia_peer
 from lbry.error import (
     DownloadSDTimeoutError, ComponentsNotStartedError, ComponentStartConditionNotMetError,
     CommandDoesNotExistError, BaseError, WalletNotFoundError, WalletAlreadyLoadedError, WalletAlreadyExistsError,
-    ConflictingInputValueError, AlreadyPurchasedError
+    ConflictingInputValueError, AlreadyPurchasedError, PrivateKeyNotFoundError
 )
 from lbry.extras import system_info
 from lbry.extras.daemon import analytics
@@ -5333,7 +5333,7 @@ class Daemon(metaclass=JSONRPCServerType):
         if len(channels) == 1:
             if for_signing and not channels[0].has_private_key:
                 # TODO: use error from lbry.error
-                raise Exception(f"Couldn't find private key for {key} '{value}'. ")
+                raise PrivateKeyNotFoundError(key, value)
             return channels[0]
         elif len(channels) > 1:
             # TODO: use error from lbry.error