Fix a crash when the app support directory couldn't be found and crashlog the reason

sources/NSFileManager+iTerm.m

@@ -111,7 +111,7 @@ NSString * const DirectoryLocationDomain = @"DirectoryLocationDomain";
                                appendPathComponent:executableName
                                              error:&error];
     if (!result) {
-        NSLog(@"Unable to find or create application support directory:\n%@", error);
+        ELog(@"Unable to find or create application support directory:\n%@", error);
     }
     return result;
 }
@@ -123,7 +123,7 @@ NSString * const DirectoryLocationDomain = @"DirectoryLocationDomain";
                                appendPathComponent:@"iTerm"
                                              error:&error];
     if (!result) {
-        NSLog(@"Unable to find or create application support directory:\n%@", error);
+        ELog(@"Unable to find or create application support directory:\n%@", error);
     }
     return result;
 }

sources/iTermDynamicProfileManager.m

@@ -38,9 +38,14 @@
 - (instancetype)init {
   self = [super init];
   if (self) {
-    _events = [[SCEvents alloc] init];
-    _events.delegate = self;
-    [_events startWatchingPaths:@[ [self dynamicProfilesPath] ]];
+      NSString *path = [self dynamicProfilesPath];
+      if (path == nil) {
+          ELog(@"Dynamic profiles path is nil");
+          return nil;
+      }
+      _events = [[SCEvents alloc] init];
+      _events.delegate = self;
+      [_events startWatchingPaths:@[ path ]];
   }
   return self;
 }