Fix GCM crash

Sources/CryptoSwift/BlockMode/GCM.swift

@@ -183,9 +183,7 @@ final class GCMModeWorker: BlockModeWorkerFinalizing {
             self.expectedTag = Array(ciphertext.suffix(GCMModeWorker.tagSize))
             // gf.ciphertextLength = gf.ciphertextLength - GCMModeWorker.tagSize
             // strip tag from the plaintext.
-            var strippedCiphertext = ciphertext
-            strippedCiphertext.removeLast(GCMModeWorker.tagSize)
-            return strippedCiphertext
+            return ciphertext[ciphertext.startIndex..<ciphertext.endIndex.advanced(by: -Swift.min(GCMModeWorker.tagSize,ciphertext.count))]
         case .detached:
             return ciphertext
         }

Tests/Tests/AESTests.swift

@@ -419,6 +419,7 @@ extension AESTests {
         // Test Case 3
         let key = Array<UInt8>(hex: "0xfeffe9928665731c6d6a8f9467308308")
         let plaintext = Array<UInt8>(hex: "0xd9313225f88406e5a55909c5aff5269a86a7a9531534f7da2e4c303d8a318a721c3c0c95956809532fcf0e2449a6b525b16aedf5aa0de657ba637b391aafd255")
+        // let plaintext = Array<UInt8>(hex: "0xd9313225f88406e5a55909")
         let iv = Array<UInt8>(hex: "0xcafebabefacedbaddecaf888")
 
         let encGCM = GCM(iv: iv, mode: .combined)