From 440bd01cd88779b6e369f47d2f3c471fb1813c4b Mon Sep 17 00:00:00 2001
From: Darshan <35736874+darshankabariya@users.noreply.github.com>
Date: Wed, 1 Jul 2026 11:48:32 +0530
Subject: [PATCH] fix: handle on-chain RPC errors gracefully during RLN setup
 (#4008)

---
 .../group_manager/on_chain/rpc_wrapper.nim    | 22 +++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/logos_delivery/waku/rln/group_manager/on_chain/rpc_wrapper.nim b/logos_delivery/waku/rln/group_manager/on_chain/rpc_wrapper.nim
index 9cb7f1ce3..c5fbc4a01 100644
--- a/logos_delivery/waku/rln/group_manager/on_chain/rpc_wrapper.nim
+++ b/logos_delivery/waku/rln/group_manager/on_chain/rpc_wrapper.nim
@@ -68,9 +68,22 @@ proc sendEthCallWithoutParams*(
   tx.data = Opt.some(byteutils.hexToSeqByte(dataSignature))
   tx.chainId = Opt.some(chainId)
 
-  let resultBytes = await ethRpc.provider.eth_call(tx, "latest")
+  # A revert / rate-limit / dropped connection raises here; return err so RLN
+  # setup fails gracefully instead of crashing the node.
+  let resultBytes =
+    try:
+      await ethRpc.provider.eth_call(tx, "latest")
+    except CatchableError as e:
+      return err("eth_call failed for " & functionSignature & ": " & e.msg)
+
   if resultBytes.len == 0:
     return err("No result returned for function call: " & functionSignature)
+  # UInt256.fromBytesBE panics (Defect) on < 32 bytes; reject short responses.
+  if resultBytes.len != 32:
+    return err(
+      "Unexpected result length (" & $resultBytes.len & " bytes) for function call: " &
+        functionSignature
+    )
   return ok(UInt256.fromBytesBE(resultBytes))
 
 proc sendEthCallWithParams*(
@@ -94,5 +107,10 @@ proc sendEthCallWithParams*(
   tx.data = Opt.some(callData)
   tx.chainId = Opt.some(chainId)
 
-  let resultBytes = await ethRpc.provider.eth_call(tx, "latest")
+  let resultBytes =
+    try:
+      await ethRpc.provider.eth_call(tx, "latest")
+    except CatchableError as e:
+      return err("eth_call failed for " & functionSignature & ": " & e.msg)
+
   return ok(resultBytes)