Minor: fixed format in exception message

[pm47]

No description provided.

[codecov-io]

Codecov Report

Merging #1199 into master will increase coverage by 0.36%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1199      +/-   ##
==========================================
+ Coverage   75.26%   75.63%   +0.36%     
==========================================
  Files         135      135              
  Lines        9082     9233     +151     
  Branches      358      371      +13     
==========================================
+ Hits         6836     6983     +147     
- Misses       2246     2250       +4

Impacted Files	Coverage Δ
...ore/src/main/scala/fr/acinq/eclair/PimpKamon.scala	50% <0%> (-50%)	⬇️
.../fr/acinq/eclair/wire/LightningMessageCodecs.scala	100% <0%> (ø)	⬆️
...chain/bitcoind/rpc/BasicBitcoinJsonRPCClient.scala	100% <0%> (ø)	⬆️
...in/bitcoind/rpc/BatchingBitcoinJsonRPCClient.scala	100% <0%> (ø)	⬆️
...e/src/main/scala/fr/acinq/eclair/api/Service.scala	71.25% <0%> (+0.8%)	⬆️
...q/eclair/blockchain/electrum/ElectrumWatcher.scala	51.72% <0%> (+0.86%)	⬆️
.../acinq/eclair/blockchain/bitcoind/ZmqWatcher.scala	97.46% <0%> (+1.24%)	⬆️
...nq/eclair/blockchain/electrum/ElectrumClient.scala	73.72% <0%> (+1.45%)	⬆️
...r-core/src/main/scala/fr/acinq/eclair/Eclair.scala	56.92% <0%> (+2.49%)	⬆️
...cinq/eclair/blockchain/bitcoind/zmq/ZMQActor.scala	94.87% <0%> (+5.12%)	⬆️
... and 1 more