Fix CSV parser and more checks for NULL ride

The CSV ride parser now checks for empty rides and returns
a NULL ride if there are no samples. In addition, the rideEditor
tries to set editorData even if the ride is NULL. Lastly, the
RideItem code for lazy reads of RideFile data didn't check for
NULL values (!).

src/CsvRideFile.cpp

@@ -296,6 +296,13 @@ RideFile *CsvFileReader::openRideFile(QFile &file, QStringList &errors) const
             qWarning("Failed to set start time");
         }
     }
-    return rideFile;
-}
 
+    // did we actually read any samples?
+    if (rideFile->dataPoints().count() > 0) {
+        return rideFile;
+    } else {
+        errors << "No samples present.";
+        delete rideFile;
+        return NULL;
+    }
+}

src/RideEditor.cpp

@@ -1082,7 +1082,7 @@ void
 RideEditor::rideSelected()
 {
     RideItem *current = main->rideItem();
-    if (!current) return;
+    if (!current || !current->ride()) return;
 
     ride = current;
 

src/RideItem.cpp

@@ -46,6 +46,8 @@ RideFile *RideItem::ride()
     // open the ride file
     QFile file(path + "/" + fileName);
     ride_ = RideFileFactory::instance().openRideFile(file, errors_);
+    if (ride_ == NULL) return NULL; // failed to read ride
+
     setDirty(false); // we're gonna use on-disk so by
                      // definition it is clean - but do it *after*
                      // we read the file since it will almost