pytype: only output the "pytype crashed" message on error

If pytype did not crash while generating stub, that message is kind of
confusing. It seems simple enough to avoid it in this case.

contrib/check-pytype.sh

@@ -1,131 +1,133 b''
 #!/bin/sh
 
 set -e
 set -u
 
 cd `hg root`
 
 # Many of the individual files that are excluded here confuse pytype
 # because they do a mix of Python 2 and Python 3 things
 # conditionally. There's no good way to help it out with that as far as
 # I can tell, so let's just hide those files from it for now. We should
 # endeavor to empty this list out over time, as some of these are
 # probably hiding real problems.
 #
 # hgext/absorb.py               # [attribute-error]
 # hgext/bugzilla.py             # [pyi-error], [attribute-error]
 # hgext/convert/bzr.py          # [attribute-error]
 # hgext/convert/cvs.py          # [attribute-error], [wrong-arg-types]
 # hgext/convert/cvsps.py        # [attribute-error]
 # hgext/convert/p4.py           # [wrong-arg-types] (__file: mercurial.utils.procutil._pfile -> IO)
 # hgext/convert/subversion.py   # [attribute-error], [name-error], [pyi-error]
 # hgext/fastannotate/context.py # no linelog.copyfrom()
 # hgext/fastannotate/formatter.py  # [unsupported-operands]
 # hgext/fsmonitor/__init__.py   # [name-error]
 # hgext/git/__init__.py         # [attribute-error]
 # hgext/githelp.py              # [attribute-error] [wrong-arg-types]
 # hgext/hgk.py                  # [attribute-error]
 # hgext/histedit.py             # [attribute-error], [wrong-arg-types]
 # hgext/keyword.py              # [attribute-error]
 # hgext/largefiles/storefactory.py  # [attribute-error]
 # hgext/lfs/__init__.py         # [attribute-error]
 # hgext/narrow/narrowbundle2.py # [attribute-error]
 # hgext/narrow/narrowcommands.py    # [attribute-error], [name-error]
 # hgext/rebase.py               # [attribute-error]
 # hgext/remotefilelog/basepack.py   # [attribute-error], [wrong-arg-count]
 # hgext/remotefilelog/basestore.py  # [attribute-error]
 # hgext/remotefilelog/contentstore.py   # [missing-parameter], [wrong-keyword-args], [attribute-error]
 # hgext/remotefilelog/fileserverclient.py  # [attribute-error]
 # hgext/remotefilelog/shallowbundle.py     # [attribute-error]
 # hgext/remotefilelog/remotefilectx.py  # [module-attr] (This is an actual bug)
 # hgext/sqlitestore.py          # [attribute-error]
 # hgext/zeroconf/__init__.py    # bytes vs str; tests fail on macOS
 #
 # mercurial/bundlerepo.py       # no vfs and ui attrs on bundlerepo
 # mercurial/context.py          # many [attribute-error]
 # mercurial/crecord.py          # tons of [attribute-error], [module-attr]
 # mercurial/debugcommands.py    # [wrong-arg-types]
 # mercurial/dispatch.py         # initstdio: No attribute ... on TextIO [attribute-error]
 # mercurial/exchange.py         # [attribute-error]
 # mercurial/hgweb/hgweb_mod.py  # [attribute-error], [name-error], [wrong-arg-types]
 # mercurial/hgweb/server.py     # [attribute-error], [name-error], [module-attr]
 # mercurial/hgweb/wsgicgi.py    # confused values in os.environ
 # mercurial/httppeer.py         # [attribute-error], [wrong-arg-types]
 # mercurial/interfaces          # No attribute 'capabilities' on peer [attribute-error]
 # mercurial/keepalive.py        # [attribute-error]
 # mercurial/localrepo.py        # [attribute-error]
 # mercurial/manifest.py         # [unsupported-operands], [wrong-arg-types]
 # mercurial/minirst.py          # [unsupported-operands], [attribute-error]
 # mercurial/pure/osutil.py      # [invalid-typevar], [not-callable]
 # mercurial/pure/parsers.py     # [attribute-error]
 # mercurial/repoview.py         # [attribute-error]
 # mercurial/testing/storage.py  # tons of [attribute-error]
 # mercurial/unionrepo.py        # ui, svfs, unfiltered [attribute-error]
 # mercurial/win32.py            # [not-callable]
 # mercurial/wireprotoframing.py # [unsupported-operands], [attribute-error], [import-error]
 # mercurial/wireprotov1peer.py  # [attribute-error]
 # mercurial/wireprotov1server.py  # BUG?: BundleValueError handler accesses subclass's attrs
 
 # TODO: use --no-cache on test server?  Caching the files locally helps during
 #       development, but may be a hinderance for CI testing.
 
 # TODO: include hgext and hgext3rd
 
 pytype -V 3.7 --keep-going --jobs auto \
     doc/check-seclevel.py hgdemandimport hgext mercurial \
     -x hgext/absorb.py \
     -x hgext/bugzilla.py \
     -x hgext/convert/bzr.py \
     -x hgext/convert/cvs.py \
     -x hgext/convert/cvsps.py \
     -x hgext/convert/p4.py \
     -x hgext/convert/subversion.py \
     -x hgext/fastannotate/context.py \
     -x hgext/fastannotate/formatter.py \
     -x hgext/fsmonitor/__init__.py \
     -x hgext/git/__init__.py \
     -x hgext/githelp.py \
     -x hgext/hgk.py \
     -x hgext/histedit.py \
     -x hgext/keyword.py \
     -x hgext/largefiles/storefactory.py \
     -x hgext/lfs/__init__.py \
     -x hgext/narrow/narrowbundle2.py \
     -x hgext/narrow/narrowcommands.py \
     -x hgext/rebase.py \
     -x hgext/remotefilelog/basepack.py \
     -x hgext/remotefilelog/basestore.py \
     -x hgext/remotefilelog/contentstore.py \
     -x hgext/remotefilelog/fileserverclient.py \
     -x hgext/remotefilelog/remotefilectx.py \
     -x hgext/remotefilelog/shallowbundle.py \
     -x hgext/sqlitestore.py \
     -x hgext/zeroconf/__init__.py \
     -x mercurial/bundlerepo.py \
     -x mercurial/context.py \
     -x mercurial/crecord.py \
     -x mercurial/debugcommands.py \
     -x mercurial/dispatch.py \
     -x mercurial/exchange.py \
     -x mercurial/hgweb/hgweb_mod.py \
     -x mercurial/hgweb/server.py \
     -x mercurial/hgweb/wsgicgi.py \
     -x mercurial/httppeer.py \
     -x mercurial/interfaces \
     -x mercurial/keepalive.py \
     -x mercurial/localrepo.py \
     -x mercurial/manifest.py \
     -x mercurial/minirst.py \
     -x mercurial/pure/osutil.py \
     -x mercurial/pure/parsers.py \
     -x mercurial/repoview.py \
     -x mercurial/testing/storage.py \
     -x mercurial/thirdparty \
     -x mercurial/unionrepo.py \
     -x mercurial/win32.py \
     -x mercurial/wireprotoframing.py \
     -x mercurial/wireprotov1peer.py \
     -x mercurial/wireprotov1server.py
 
-echo 'pytype crashed while generating the following type stubs:'
-find .pytype/pyi -name '*.pyi' | xargs grep -l '# Caught error' | sort
+if find .pytype/pyi -name '*.pyi' | xargs grep -ql '# Caught error'; then
+    echo 'pytype crashed while generating the following type stubs:'
+    find .pytype/pyi -name '*.pyi' | xargs grep -l '# Caught error' | sort
+fi