Fix error with deprecation warnings and legacy importers (#339)

Author: jathak

lib/src/legacy/utils.ts

@@ -38,7 +38,13 @@ export function removeLegacyImporter(string: string): string {
 // syntax.
 export function removeLegacyImporterFromSpan(span: SourceSpan): SourceSpan {
   if (!span.url) return span;
-  return {...span, url: new URL(removeLegacyImporter(span.url.toString()))};
+  return {
+    ...span,
+    url: new URL(
+      removeLegacyImporter(span.url.toString()),
+      pathToFileURL(process.cwd())
+    ),
+  };
 }
 
 // Converts [path] to a `file:` URL and adds the [legacyImporterProtocolPrefix]