The response from dataproviders here can return data===null in additi…

…on to being simply undefined. This corrects the logic shortcutting and prevents errors like 'Cannot read property 'min' of null'

client/galaxy/scripts/viz/trackster/tracks.js

@@ -2507,7 +2507,7 @@ extend(Track.prototype, Drawable.prototype, {
             var data = result.data;
 
             // Tracks may not have stat data either because there is no data or data is not yet ready.
-            if (data !== undefined && data.min !== undefined && data.max !== undefined) {
+            if (data && data.min !== undefined && data.max !== undefined) {
                 // Compute default minimum and maximum values
                 var min_value = data.min,
                     max_value = data.max;

lib/galaxy/webapps/galaxy/api/datasets.py

@@ -154,7 +154,7 @@ def _data( self, trans, dataset, chrom, low, high, start_val=0, max_vals=None, *
         if msg:
             return msg
 
-        # Get datasources and check for essages.
+        # Get datasources and check for messages.
         data_sources = dataset.get_datasources( trans )
         messages_list = [ data_source_dict[ 'message' ] for data_source_dict in data_sources.values() ]
         return_message = self._get_highest_priority_msg( messages_list )
@@ -249,7 +249,7 @@ def _raw_data( self, trans, dataset, provider=None, **kwargs ):
 
         registry = trans.app.data_provider_registry
 
-        # allow the caller to specifiy which provider is used
+        # allow the caller to specify which provider is used
         #   pulling from the original providers if possible, then the new providers
         if provider:
             if provider in registry.dataset_type_name_to_data_provider: