Fix test throw error if from balance is 0

assembly/__tests__/env-coins.spec.ts

@@ -60,18 +60,6 @@ describe('Testing env coins related functions', () => {
     expect(env.balanceOf(testAddress2.toString())).toBe(amount);
   });
 
-  it('transferCoins to mock address created with addAddressToLedger', () => {
-    addAddressToLedger(testAddress3.toString());
-    const amount: u64 = 100;
-    const receiverCurrentBalance = env.balanceOf(testAddress3.toString());
-    // given
-    expect(receiverCurrentBalance).toBe(0);
-    // when
-    env.transferCoins(testAddress3.toString(), amount);
-    // then
-    expect(env.balanceOf(testAddress3.toString())).toBe(amount);
-  });
-
   it('get the balance of an address', () => {
     const amount: u64 = 100;
     // given

vm-mock/vm.js

@@ -699,20 +699,21 @@ export default function createMockedABI(
         if (!ledger.has(fromAddress)) {
           ERROR(`Sending address ${fromAddress} does not exist in ledger.`);
         }
-        const senderBalance = ledger.get(fromAddress).balance;
 
+        // We should not have this case, but someone could add a ledger.set without a balance
+        // Typescript could be used to avoid this kind of error
+        if (ledger.get(fromAddress).balance === undefined) {
+          ERROR('not enough balance to transfer ' + amount + ' coins.');
+        }
+
+        const senderBalance = ledger.get(fromAddress).balance;
         if (senderBalance < BigInt(amount)) {
           ERROR('not enough balance to transfer ' + amount + ' coins.');
         }
 
-        // We should not have this case, but someone could add a ledger.set without a balance
-        // Typescript could be used to avoid this kind of error
         if (ledger.get(toAddress).balance === undefined) {
           ledger.get(toAddress).balance = BigInt(0);
         }
-        if (ledger.get(fromAddress).balance === undefined) {
-          ledger.get(fromAddress).balance = BigInt(0);
-        }
 
         ledger.get(toAddress).balance += BigInt(amount);
         ledger.get(fromAddress).balance -= BigInt(amount);