pw_doctor: Improve deleted file error message
pw_doctor: Improve deleted file error message

Previously the user just got an exception.

Change-Id: Iad2271640e650b7a21b234f8908b5eebd9343083
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/97740
Reviewed-by: Jonathan Cardy <b541952bb80ecc8bd0f16a279d10badd687d1513@google.com>
Pigweed-Auto-Submit: Rob Mohr <d07614a8a0b466db08f68224f87d738b0f9615cf@google.com>
Commit-Queue: Auto-Submit <14637eda5603879df170705285bf30f5996692f0@pigweed.google.com.iam.gserviceaccount.com>

google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed,google/pigweed