bug: incorrect error message when adding tests for incremental table type

[ashish10alex]

According to the following line we should get a compilation message when trying to add a unit test for action type incremental. However we get a generic compilation error message instead. Same experience was reported here.

Expected error message

dataform/core/actions/test.ts

Line 185 in 412d523

new Error("Running tests on incremental datasets is not yet supported."),

Error message we get due to this check in prior lines

dataform/core/actions/test.ts

Lines 178 to 182 in 412d523

	if (!(dataset && (dataset instanceof Table || dataset instanceof View))) {
	this.session.compileError(
	new Error(`Dataset ${stringifyResolvable(this.datasetToTest)} could not be found.`),
	this.proto.fileName
	);