Merge pull request #5506 from asottile/fix_no_terminal

Fix crash when discovery fails while using `-p no:terminal`

src/_pytest/nodes.py

@@ -329,7 +329,7 @@ class Collector(Node):
 
         # Respect explicit tbstyle option, but default to "short"
         # (None._repr_failure_py defaults to "long" without "fulltrace" option).
-        tbstyle = self.config.getoption("tbstyle")
+        tbstyle = self.config.getoption("tbstyle", "auto")
         if tbstyle == "auto":
             tbstyle = "short"