Add “group creation failed” error message.

// FREEBIE

src/Messages/Interactions/TSErrorMessage.h

@@ -21,6 +21,7 @@ typedef NS_ENUM(int32_t, TSErrorMessageType) {
     TSErrorMessageInvalidVersion,
     TSErrorMessageNonBlockingIdentityChange,
     TSErrorMessageUnknownContactBlockOffer,
+    TSErrorMessageGroupCreationFailed,
 };
 
 - (instancetype)initWithCoder:(NSCoder *)coder NS_DESIGNATED_INITIALIZER;

src/Messages/Interactions/TSErrorMessage.m

@@ -115,6 +115,9 @@ NSUInteger TSErrorMessageSchemaVersion = 1;
         case TSErrorMessageUnknownContactBlockOffer:
             return NSLocalizedString(@"UNKNOWN_CONTACT_BLOCK_OFFER",
                 @"Message shown in conversation view that offers to block an unknown user.");
+        case TSErrorMessageGroupCreationFailed:
+            return NSLocalizedString(@"GROUP_CREATION_FAILED",
+                @"Message shown in conversation view that indicates there were issues with group creation.");
         default:
             return NSLocalizedString(@"ERROR_MESSAGE_UNKNOWN_ERROR", @"");
             break;