Fix buggy string comparison in OCW pallet example (#8602)

substrate/frame/example-offchain-worker/src/lib.rs

@@ -612,18 +612,17 @@ impl<T: Config> Pallet<T> {
 	/// Returns `None` when parsing failed or `Some(price in cents)` when parsing is successful.
 	fn parse_price(price_str: &str) -> Option<u32> {
 		let val = lite_json::parse_json(price_str);
-		let price = val.ok().and_then(|v| match v {
+		let price = match val.ok()? {
 			JsonValue::Object(obj) => {
-				let mut chars = "USD".chars();
-				obj.into_iter()
-					.find(|(k, _)| k.iter().all(|k| Some(*k) == chars.next()))
-					.and_then(|v| match v.1 {
-						JsonValue::Number(number) => Some(number),
-						_ => None,
-					})
+				let (_, v) = obj.into_iter()
+					.find(|(k, _)| k.iter().copied().eq("USD".chars()))?;
+				match v {
+					JsonValue::Number(number) => number,
+					_ => return None,
+				}
 			},
-			_ => None
-		})?;
+			_ => return None,
+		};
 
 		let exp = price.fraction_length.checked_sub(2).unwrap_or(0);
 		Some(price.integer as u32 * 100 + (price.fraction / 10_u64.pow(exp)) as u32)