Revert "internal/lsp: modify check for a missing package"

This reverts commit 55ee3a41311a7fa2447fd773c868f0d13555f695.

Reason for revert: <forgot to run trybots>

Change-Id: I6d0890e2514841244a2a1f8ca861107c5de1f8aa
Reviewed-on: https://go-review.googlesource.com/c/tools/+/184040
Reviewed-by: Suzy Mueller <suzmue@golang.org>
diff --git a/internal/lsp/cache/load.go b/internal/lsp/cache/load.go
index 85eb2c6..913ef4a 100644
--- a/internal/lsp/cache/load.go
+++ b/internal/lsp/cache/load.go
@@ -118,8 +118,7 @@
 			return nil, pkg.Errors, fmt.Errorf("package %s has errors, skipping type-checking", pkg.PkgPath)
 		}
 		for importPath, importPkg := range pkg.Imports {
-			// If we encounter a package we cannot import, mark it as missing.
-			if len(importPkg.CompiledGoFiles) == 0 {
+			if len(importPkg.Errors) > 0 {
 				if f.missingImports == nil {
 					f.missingImports = make(map[packagePath]struct{})
 				}