I have been trying to deploy apex classes to a Trailhead Playgound as well as a developer org, but I receive the error "SFDX: Deploy Source to Org failed to run" in VS Code. 

Did I miss something when I set-up VS Code?

• Salesforce CLI is up to date
• All extensions are up to date
• The orgs in question have been authorized successfully
• The CLI appears to be installed correctly (when I run "sfdx" in the Terminal, I receive the Salesforce CLI menu)

This is the Salesforce CLI output:
Starting SFDX: Deploy Source to Org
11:35:46.868 sfdx force:source:deploy --sourcepath c:\Salesforce\VSCodeQuickStart\force-app --json --loglevel fatal
11:35:48.630 sfdx force:source:deploy --sourcepath c:\Salesforce\VSCodeQuickStart\force-app --json --loglevel fatal ended with exit code 1

Any help would be much appreciated!