Avoid crashing for RETDecimal.max().formated(...) (#1044)

RadixWallet/EngineKit/RETDecimal+Extensions.swift

@@ -246,7 +246,23 @@ extension RETDecimal {
 		let integerCount = UInt(Swift.max(digits.count - RETDecimal.scale, 1))
 		if integerCount > totalPlaces {
 			let scale = RETDecimal(exponent: integerCount - totalPlaces)
-			return (self / scale).rounded(decimalPlaces: 0) * scale
+			let base = self / scale
+			let decimalPlaces: UInt = 0
+			let base_rounded = base.rounded(decimalPlaces: decimalPlaces)
+
+			do {
+				return try base_rounded.mul(other: scale)
+			} catch {
+				// we overflowed which will happen if we are using RETDecimal.max()
+				// instead of using `base.rounded(decimalPlaces: 0)` which uses
+				// rounding mode `toNearestMidpointAwayFromZero` we will use
+				// `toZero` to avoid overflow.
+				let safeBase = try! base.round(
+					decimalPlaces: Int32(decimalPlaces),
+					roundingMode: .toZero
+				)
+				return safeBase * scale
+			}
 		} else {
 			// The remaining digits are decimals and we keep up to totalPlaces of them
 			let decimalsToKeep = totalPlaces - integerCount

RadixWalletTests/EngineKitTests/DecimalTests.swift

@@ -274,15 +274,17 @@ final class DecimalTests: TestCase {
 	}
 
 	func test_format_decimal() throws {
-		func doTest(_ decimalString: String, expected: String, line: UInt = #line) throws {
+		func doTest(_ decimal: RETDecimal, expected: String, line: UInt = #line) throws {
 			let locale = Locale(identifier: "en_US_POSIX")
-			let decimal = try RETDecimal(value: decimalString)
 			let actual = decimal.formatted(locale: locale, totalPlaces: 8, useGroupingSeparator: false)
 			XCTAssertEqual(actual, expected, line: line)
 		}
+		func doTest(_ decimalString: String, expected: String, line: UInt = #line) throws {
+			try doTest(RETDecimal(value: decimalString), expected: expected, line: line)
+		}
 
+		try doTest(RETDecimal.max(), expected: "3.138e39")
 		try doTest("0.009999999999999", expected: "0.01")
-
 		try doTest("12341234", expected: "12.341234 M")
 		try doTest("1234123.4", expected: "1.2341234 M")
 		try doTest("123456.34", expected: "123456.34")