fix empty err msg when txfee is out of range

src/libxrpl/protocol/TER.cpp

@@ -201,6 +201,7 @@ transResults()
         MAKE_ERROR(temINVALID_COUNT,             "Malformed: Count field outside valid range."),
         MAKE_ERROR(temSEQ_AND_TICKET,            "Transaction contains a TicketSequence and a non-zero Sequence."),
         MAKE_ERROR(temBAD_NFTOKEN_TRANSFER_FEE,  "Malformed: The NFToken transfer fee must be between 1 and 5000, inclusive."),
+        MAKE_ERROR(temBAD_MPTOKEN_TRANSFER_FEE,  "Malformed: The MPToken transfer fee must be between 1 and 5000, inclusive."),
         MAKE_ERROR(temXCHAIN_EQUAL_DOOR_ACCOUNTS,       "Malformed: Bridge must have unique door accounts."),
         MAKE_ERROR(temXCHAIN_BAD_PROOF,          "Malformed: Bad cross-chain claim proof."),
         MAKE_ERROR(temXCHAIN_BRIDGE_BAD_ISSUES,      "Malformed: Bad bridge issues."),

src/test/app/MPToken_test.cpp

@@ -58,7 +58,7 @@ class MPToken_test : public beast::unit_test::suite
                  .metadata = "test",
                  .err = temMALFORMED});
 
-            // tries to set a txfee while not enabling transfer
+            // tries to set a txfee greater than max
             mptAlice.create(
                 {.maxAmt = 100,
                  .assetScale = 0,
@@ -67,6 +67,14 @@ class MPToken_test : public beast::unit_test::suite
                  .flags = tfMPTCanTransfer,
                  .err = temBAD_MPTOKEN_TRANSFER_FEE});
 
+            // tries to set a txfee while not enabling transfer
+            mptAlice.create(
+                {.maxAmt = 100,
+                 .assetScale = 0,
+                 .transferFee = maxTransferFee,
+                 .metadata = "test",
+                 .err = temMALFORMED});
+
             // empty metadata returns error
             mptAlice.create(
                 {.maxAmt = 100,