Fallback to Zerion Balance Fetching on Failed Safe Attempt (#18)

We are hitting some failed balance fetching on Avalanche:

```
Error fetching Safe balances: TypeError: fetch failed
    at node:internal/deps/undici/undici:13185:13
    at processTicksAndRejections (node:internal/process/task_queues:95:5)
    at runNextTicks (node:internal/process/task_queues:64:3)
    at process.processImmediate (node:internal/timers:454:9)
    at process.callbackTrampoline (node:internal/async_hooks:130:17)
    at async getSafeBalances (/var/task/node_modules/@bitte-ai/agent-sdk/dist/cjs/evm/safe.js:40:26)
    at async Promise.all (index 0) {
    [cause]: ConnectTimeoutError: Connect Timeout Error (attempted addresses: 108.138.85.41:443)
    at onConnectTimeout (node:internal/deps/undici/undici:2331:28)
    at node:internal/deps/undici/undici:2283:50
    at Immediate._onImmediate (node:internal/deps/undici/undici:2315:13)
    at process.processImmediate (node:internal/timers:483:21)
    at process.callbackTrampoline (node:internal/async_hooks:130:17) {
    code: 'UND_ERR_CONNECT_TIMEOUT'
  }
}
```

for this request: 


https://safe-transaction-avalanche.safe.global/api/v1/safes/0x454F89b3Ba39A15C198F95c2C92A20dD9D102144/balances/?trusted=false&exclude_spam=true

Attempting to temporarily navigate the Safe Balance fetching failures by
using zerion on error.

Asked about rate limiting on [Safe
Discord](https://discord.com/channels/907968493134155807/960898410037272616/1328708351516872778)

Author: bh2smith

packages/agent-sdk/src/evm/safe.ts

@@ -74,31 +74,39 @@ export async function getSafeBalances(
     if (!response.ok) {
       if (response.status === 404) {
         console.warn(`Safe not found for ${address}`);
-        if (!zerionKey) {
-          return [];
-        }
-        console.info("Zerion Key provided - using Zerion");
-        // Not a Safe, try Zerion
-        try {
-          const zerion = new ZerionAPI(zerionKey);
-          // TODO(bh2smith): This is not super efficient, but it works for now.
-          // Zerion API has its own network filter (but its not by chainID).
-          const balances = await zerion.ui.getUserBalances(address, {
-            options: { supportedChains: [chainId] },
-          });
-          return zerionToTokenBalances(balances.tokens);
-        } catch (error) {
-          console.error("Error fetching Zerion balances:", error);
-          return [];
-        }
       }
       throw new Error(`HTTP error! status: ${response.status}`);
     }
+    const data: TokenBalance[] = await response.json();
+    console.log(`Retrieved ${data.length} balances`);
+    return data;
+  } catch (error) {
+    console.warn("Error fetching Safe balances:", error);
+    return getZerionBalances(chainId, address, zerionKey);
+  }
+}
 
-    return await response.json();
+async function getZerionBalances(
+  chainId: number,
+  address: Address,
+  zerionKey?: string,
+): Promise<TokenBalance[]> {
+  if (!zerionKey) {
+    return [];
+  }
+  console.info("Zerion Key provided - using Zerion");
+  // Not a Safe, try Zerion
+  try {
+    const zerion = new ZerionAPI(zerionKey);
+    // TODO(bh2smith): This is not super efficient, but it works for now.
+    // Zerion API has its own network filter (but its not by chainID).
+    const balances = await zerion.ui.getUserBalances(address, {
+      options: { supportedChains: [chainId] },
+    });
+    return zerionToTokenBalances(balances.tokens);
   } catch (error) {
-    console.error("Error fetching Safe balances:", error);
-    throw error;
+    console.error("Error fetching Zerion balances:", error);
+    return [];
   }
 }