pw_presubmit: Fix link to static analyzer report

Missing field in the error message points to an individual report file
instead of the top-level report page.

Change-Id: Id7e679407f525973f4bbfb4630167c1abeef928a
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/35580
Pigweed-Auto-Submit: Prashanth Swaminathan <prashanthsw@google.com>
Reviewed-by: Anthony DiGirolamo <tonymd@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/pw_presubmit/py/pw_presubmit/pigweed_presubmit.py b/pw_presubmit/py/pw_presubmit/pigweed_presubmit.py
index 5b4b677..d136b77 100755
--- a/pw_presubmit/py/pw_presubmit/pigweed_presubmit.py
+++ b/pw_presubmit/py/pw_presubmit/pigweed_presubmit.py
@@ -546,7 +546,7 @@
                                       reports[0].parent)
         _LOG.error('Static analyzer found errors: %s', archive)
         _LOG.error('To view report, open: %s',
-                   Path(reports[0]).joinpath('index.html'))
+                   Path(reports[0]).parent.joinpath('index.html'))
         raise PresubmitFailure