Prefer to fail with InputTooShort over InvalidWord

libsession-util/src/test/java/org/session/libsignal/crypto/MnemonicCodecTest.kt

@@ -35,14 +35,14 @@ class MnemonicCodecTest {
 
     @Test
     fun `decode one invalid word that is too short`() {
-        assertThrows(InvalidWord::class.java) {
+        assertThrows(InputTooShort::class.java) {
             codec.decode("a")
         }
     }
 
     @Test
     fun `decode one invalid word`() {
-        assertThrows(InvalidWord::class.java) {
+        assertThrows(InputTooShort::class.java) {
             codec.decode("abcd")
         }
     }
@@ -99,7 +99,7 @@ class MnemonicCodecTest {
 
     @Test
     fun `decodeMnemonicOrHexAsByteArray with account id throws`() {
-        assertThrows(InvalidWord::class.java) {
+        assertThrows(InputTooShort::class.java) {
             codec.decodeMnemonicOrHexAsByteArray("0582e1421da6f584a4795d30b654b4f25fed860afdf081075cb26a2b997e492f14").let(Hex::toStringCondensed)
         }
     }
@@ -109,7 +109,7 @@ class MnemonicCodecTest {
         // throws InvalidWord as 0f2ccde528622876b8f16e14db97dafcg is not a valid word on the english wordlist.
         // It is also not a valid hex string, but we assume that a non-hex string is a recovery password.
 
-        assertThrows(InvalidWord::class.java) {
+        assertThrows(InputTooShort::class.java) {
             codec.decodeMnemonicOrHexAsByteArray("0f2ccde528622876b8f16e14db97dafcg").let(Hex::toStringCondensed)
         }
     }

libsignal/src/main/java/org/session/libsignal/crypto/MnemonicCodec.kt

@@ -83,8 +83,8 @@ class MnemonicCodec(private val loadFileContents: (String) -> String) {
         val prefixLength = languageConfiguration.prefixLength
         val n = truncatedWordSet.size.toLong()
 
-        if (mnemonic.isEmpty()) throw DecodingError.InputTooShort
-        if (words.isEmpty()) throw DecodingError.InputTooShort
+        // Check preconditions
+        if (words.size < 13) throw DecodingError.InputTooShort
 
         fun String.prefix() = substring(0 until prefixLength)
 
@@ -96,9 +96,6 @@ class MnemonicCodec(private val loadFileContents: (String) -> String) {
         val wordIndexes = wordPrefixes.map { truncatedWordSet.indexOf(it) }
             .onEach { if (it < 0) throw DecodingError.InvalidWord }
 
-        // Check preconditions
-        if (words.size < 13) throw DecodingError.InputTooShort
-
         // Verify checksum
         val checksumIndex = determineChecksumIndex(words.dropLast(1), prefixLength)
         val expectedChecksumWord = words[checksumIndex]