Return an empty list rather than a set if unable to construct the check list to have a more consistent return type.
@@ -62,7 +62,7 @@ class ClangTidy(analyzer_base.SourceAnalyzer):
result = subprocess.check_output(command, env=env)
self.__parse_checkers(result)
except (subprocess.CalledProcessError, OSError):
- return {}
+ return []
return self.checkers
