[FIX] Specs conformant error codes (#693)

* error codes must follow spec

* make format

cashu/core/errors.py

@@ -18,6 +18,19 @@ class NotAllowedError(CashuError):
     def __init__(self, detail: Optional[str] = None, code: Optional[int] = None):
         super().__init__(detail or self.detail, code=code or self.code)
 
+class OutputsAlreadySignedError(CashuError):
+    detail = "outputs have already been signed before."
+    code = 10002
+
+    def __init__(self, detail: Optional[str] = None, code: Optional[int] = None):
+        super().__init__(detail or self.detail, code=code or self.code)
+
+class InvalidProofsError(CashuError):
+    detail = "proofs could not be verified"
+    code = 10003
+
+    def __init__(self, detail: Optional[str] = None, code: Optional[int] = None):
+        super().__init__(detail or self.detail, code=code or self.code)
 
 class TransactionError(CashuError):
     detail = "transaction error"
@@ -63,6 +76,11 @@ class TransactionUnitError(TransactionError):
     def __init__(self, detail):
         super().__init__(detail, code=self.code)
 
+class TransactionAmountExceedsLimitError(TransactionError):
+    code = 11006
+
+    def __init__(self, detail):
+        super().__init__(detail, code=self.code)
 
 class KeysetError(CashuError):
     detail = "keyset error"

cashu/mint/ledger.py

@@ -39,6 +39,7 @@ from ..core.errors import (
     NotAllowedError,
     QuoteNotPaidError,
     QuoteSignatureInvalidError,
+    TransactionAmountExceedsLimitError,
     TransactionError,
 )
 from ..core.helpers import sum_proofs
@@ -403,7 +404,7 @@ class Ledger(LedgerVerification, LedgerSpendingConditions, LedgerTasks, LedgerFe
         if not quote_request.amount > 0:
             raise TransactionError("amount must be positive")
         if settings.mint_max_peg_in and quote_request.amount > settings.mint_max_peg_in:
-            raise NotAllowedError(
+            raise TransactionAmountExceedsLimitError(
                 f"Maximum mint amount is {settings.mint_max_peg_in} sat."
             )
         if settings.mint_peg_out_only:

cashu/mint/verification.py

@@ -15,8 +15,10 @@ from ..core.crypto import b_dhke
 from ..core.crypto.secp import PublicKey
 from ..core.db import Connection, Database
 from ..core.errors import (
+    InvalidProofsError,
     NoSecretInProofsError,
     NotAllowedError,
+    OutputsAlreadySignedError,
     SecretTooLongError,
     TransactionError,
     TransactionUnitError,
@@ -79,7 +81,7 @@ class LedgerVerification(
             raise TransactionError("duplicate proofs.")
         # Verify ecash signatures
         if not all([self._verify_proof_bdhke(p) for p in proofs]):
-            raise TransactionError("could not verify proofs.")
+            raise InvalidProofsError()
         # Verify input spending conditions
         if not all([self._verify_input_spending_conditions(p) for p in proofs]):
             raise TransactionError("validation of input spending conditions failed.")
@@ -141,7 +143,7 @@ class LedgerVerification(
         # verify that outputs have not been signed previously
         signed_before = await self._check_outputs_issued_before(outputs, conn)
         if any(signed_before):
-            raise TransactionError("outputs have already been signed before.")
+            raise OutputsAlreadySignedError()
         logger.trace(f"Verified {len(outputs)} outputs.")
 
     async def _check_outputs_issued_before(