fix: check if UTI exists (Vydia#272)

Fixes a crash if UTI is null on Mac M1 simulators:

Author: nkovacic

ios/VydiaRNFileUploader.m

@@ -110,7 +110,11 @@ + (void)setCompletionHandlerWithIdentifier: (NSString *)identifier completionHan
 - (NSString *)guessMIMETypeFromFileName: (NSString *)fileName {
     CFStringRef UTI = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, (__bridge CFStringRef)[fileName pathExtension], NULL);
     CFStringRef MIMEType = UTTypeCopyPreferredTagWithClass(UTI, kUTTagClassMIMEType);
-    CFRelease(UTI);
+    
+    if (UTI) {
+        CFRelease(UTI);
+    }
+  
     if (!MIMEType) {
         return @"application/octet-stream";
     }