fix(tracer): adds vm error to flatCallTracer error field if exists (#3374)

## What ❔

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- Updates `flatCallTracer` error to include vm error if it exists 

## Why ❔

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are the principles behind them? -->
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- MM has requested that if an error exists we should populate within
`flatCallTracer` as this is what others do, prior to this PR it was only
revert_reason introduced here:
#3306. However, if we have
a vm error the error field is not populated as seen in this tx:
`0x6c85bf34666dcdaa885f2bc6e95186029d2b25f2a3bbdff21c36878e2d4a19ed`
which failed due to a vm panic.

## Checklist

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- [x] PR title corresponds to the body of PR (we generate changelog
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lint`.

Author: dutterbutter

core/node/api_server/src/web3/namespaces/debug.rs

@@ -96,16 +96,22 @@ impl DebugNamespace {
             CallType::NearCall => unreachable!("We have to filter our near calls before"),
         };
 
-        let (result, error) = if let Some(error) = call.revert_reason {
-            (None, Some(error))
-        } else {
-            (
+        let (result, error) = match (call.revert_reason, call.error) {
+            (Some(revert_reason), _) => {
+                // If revert_reason exists, it takes priority over VM error
+                (None, Some(revert_reason))
+            }
+            (None, Some(vm_error)) => {
+                // If no revert_reason but VM error exists
+                (None, Some(vm_error))
+            }
+            (None, None) => (
                 Some(CallResult {
                     output: web3::Bytes::from(call.output),
                     gas_used: U256::from(call.gas_used),
                 }),
                 None,
-            )
+            ),
         };
 
         calls.push(DebugCallFlat {