Working on CodingKey

Author: colemancda

Sources/CodingKey.swift

@@ -55,7 +55,13 @@ public extension TLVCodingKey where Self: CaseIterable, Self: RawRepresentable,
 
 internal extension TLVTypeCode {
 
-    init? <K: CodingKey> (codingKey: K) {
+    enum CodingKeyError: Error {
+        
+        case missingIntegerValue
+        case invalidIntegerValue(Int)
+    }
+    
+    init<K: CodingKey> (codingKey: K) throws {
 
         if let tlvCodingKey = codingKey as? TLVCodingKey {
 
@@ -65,17 +71,18 @@ internal extension TLVTypeCode {
 
             guard intValue <= Int(UInt8.max),
                 intValue >= Int(UInt8.min)
-                else { return nil }
+                else { throw CodingKeyError.invalidIntegerValue(intValue) }
 
             self.init(rawValue: UInt8(intValue))
 
-        } else if MemoryLayout<K>.size == MemoryLayout<UInt8>.size {
+        } else if MemoryLayout<K>.size == MemoryLayout<UInt8>.size,
+            Mirror(reflecting: codingKey).displayStyle == .enum {
 
             self.init(rawValue: unsafeBitCast(codingKey, to: UInt8.self))
 
         } else {
 
-            return nil
+            throw CodingKeyError.missingIntegerValue
         }
     }
 }