Revert "Use Coin's FromStr impl in FromStr impl of Coins"

This reverts commit 39dc511.

packages/std/src/coins.rs

@@ -1,3 +1,4 @@
+use std::any::type_name;
 use std::collections::BTreeMap;
 use std::fmt;
 use std::str::FromStr;
@@ -80,9 +81,29 @@ impl FromStr for Coins {
             return Ok(Self::default());
         }
 
+        // TODO: use FromStr impl for Coin once it's merged
+        let parse_coin_str = |s: &str| -> StdResult<Coin> {
+            for (i, c) in s.chars().enumerate() {
+                if !c.is_ascii_digit() {
+                    let amount = Uint128::from_str(&s[..i]).map_err(|_| {
+                        StdError::generic_err(
+                            "Parsing Coin: Missing amount or non-digit characters in amount",
+                        )
+                    })?;
+                    let denom = String::from(&s[i..]);
+                    return Ok(Coin { amount, denom });
+                }
+            }
+
+            Err(StdError::parse_err(
+                type_name::<Coin>(),
+                format!("invalid coin string: {s}"),
+            ))
+        };
+
         Ok(s.split(',')
-            .map(Coin::from_str)
-            .collect::<Result<Vec<_>, _>>()?
+            .map(parse_coin_str)
+            .collect::<StdResult<Vec<_>>>()?
             .try_into()?)
     }
 }