minor refactor on how to show error messages when the mnemonic is incorrect

Session/Onboarding/LoadAccountScreen.swift

@@ -85,7 +85,14 @@ struct LoadAccountScreen: View {
             hexEncodedSeed = try Mnemonic.decode(mnemonic: mnemonic)
         } catch {
             if let decodingError = error as? Mnemonic.DecodingError {
-                errorString = decodingError.errorDescription
+                switch decodingError {
+                    case .inputTooShort, .missingLastWord:
+                        errorString = "recoveryPasswordErrorMessageShort".localized()
+                    case .invalidWord, .verificationFailed:
+                        errorString = "recoveryPasswordErrorMessageIncorrect".localized()
+                    default:
+                        errorString = "recoveryPasswordErrorMessageGeneric".localized()
+                }
             } else {
                 errorString = "recoveryPasswordErrorMessageGeneric".localized()
             }

SessionUtilitiesKit/Crypto/Mnemonic.swift

@@ -67,17 +67,6 @@ public enum Mnemonic {
     
     public enum DecodingError : LocalizedError {
         case generic, inputTooShort, missingLastWord, invalidWord, verificationFailed
-        
-        public var errorDescription: String {
-            switch self {
-                case .inputTooShort:
-                    return "recoveryPasswordErrorMessageShort".localized()
-                case .invalidWord:
-                    return "recoveryPasswordErrorMessageIncorrect".localized()
-                default:
-                    return "recoveryPasswordErrorMessageGeneric".localized()
-            }
-        }
     }
     
     public static func hash(hexEncodedString string: String, language: Language = .english) -> String {