From 9354e797b69519aec723356583bd4c48b916c6b1 Mon Sep 17 00:00:00 2001
From: Michael Vines <mvines@gmail.com>
Date: Tue, 15 Jan 2019 16:14:24 -0800
Subject: [PATCH] Cleanly handle balance underflows

---
 wallet/src/wallet.rs | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/wallet/src/wallet.rs b/wallet/src/wallet.rs
index 9d16cc2723..c66fe20b8a 100644
--- a/wallet/src/wallet.rs
+++ b/wallet/src/wallet.rs
@@ -360,8 +360,18 @@ pub fn process_command(config: &WalletConfig) -> Result<String, Box<dyn error::E
                 .as_u64()
                 .unwrap_or(previous_balance);
 
+            if current_balance < previous_balance {
+                Err(format!(
+                    "Airdrop failed: current_balance({}) < previous_balance({})",
+                    current_balance, previous_balance
+                ))?;
+            }
             if current_balance - previous_balance < tokens {
-                Err("Airdrop failed!")?;
+                Err(format!(
+                    "Airdrop failed: Account balance increased by {} instead of {}",
+                    current_balance - previous_balance,
+                    tokens
+                ))?;
             }
             Ok(format!("Your balance is: {:?}", current_balance))
         }