message: fix diagnostics error report when there is no import for symbol
diff: @@ -133,7 +133,7 @@ export class StylableTransformer {
  this.exportRootClass(resolved.meta, classExports);
  scopedName += ' ' + classExports[resolved.symbol.name];
  } else {
  - const node = getCorrectNodeImport(_import, (node: any) => node.prop === valueMapping.from)
  + const node = getCorrectNodeImport(_import, (node: any) => node.prop === valueMapping.from);
  this.diagnostics.error(node, "Trying to import unknown file", { word: node.value })
  }
  }
  @@ -278,7 +278,11 @@ export class StylableTransformer {
  } else if (!value) {
  const importIndex = meta.imports.findIndex((imprt: Imported) => !!imprt.named[name]);
  let correctNode = getCorrectNodeImport(meta.imports[importIndex], (node: any) => node.prop === valueMapping.named)
  + if(correctNode){
  this.diagnostics.error(correctNode, `cannot find export "${name}" in "${meta.imports[importIndex].fromRelative}"`, { word: name })
  + } else {
  + //catched in the process step.
  + }
  }
  return typeof value === 'string' ? value : match;
  });
  