If you face “No base file for markup://c:” exception, 

1. Make sure you are not trying the create Lightning Web Component(LWC) with the same name as Aura Component.

Go to Lightning Components under Setup and make sure the same name is not used on existing components.

2. Right click the js-meta.xml file of the Lightning Web Component(LWC) and select “SFDX: Deploy Source to Org”.