I had made some changes to the API, to these fields (to make them optional. microsoft/vscode-cpptools-api#28 ) :

SourceFileConfiguration 

	intelliSenseMode
	standard

WorkspaceBrowseConfiguration 

	standard

They now accept undefined. But, we were waiting until we ingested the new API to make the corresponding changes to cpptools. Could you update isSourceFileConfigurationItem() to use isOptionalString() instead of isString() when validating? Perhaps consider it an error if either of these are undefined when the compilerPath is also undefined. We need compilePath to be present to auto-detect these.

Similarly for WorkspaceBrowseConfiguration in sendCustomBrowseConfiguration(). That is already using isOptionalString for standard, but should probably flag an error if it's undefined and compilerPath is also undefined.