diff --git a/spacy/syntax/transition_system.pyx b/spacy/syntax/transition_system.pyx
index 839a27b79..e1ec40e0e 100644
--- a/spacy/syntax/transition_system.pyx
+++ b/spacy/syntax/transition_system.pyx
@@ -61,7 +61,7 @@ cdef class TransitionSystem:
             offset += len(doc)
         return states
 
-    def get_oracle_sequence(self, Example example):
+    def get_oracle_sequence(self, Example example, _debug=False):
         cdef Pool mem = Pool()
         # n_moves should not be zero at this point, but make sure to avoid zero-length mem alloc
         assert self.n_moves > 0
@@ -70,6 +70,8 @@ cdef class TransitionSystem:
 
         cdef StateClass state
         states, golds, n_steps = self.init_gold_batch([example])
+        if not states:
+            return []
         state = states[0]
         gold = golds[0]
         history = []
@@ -82,30 +84,32 @@ cdef class TransitionSystem:
                     history.append(i)
                     s0 = state.S(0)
                     b0 = state.B(0)
-                    debug_log.append(" ".join((
-                        self.get_class_name(i),
-                        "S0=", (example.x[s0].text if s0 >= 0 else "__"),
-                        "B0=", (example.x[b0].text if b0 >= 0 else "__"),
-                        "S0 head?", str(state.has_head(state.S(0))),
-                    )))
+                    if _debug:
+                        debug_log.append(" ".join((
+                            self.get_class_name(i),
+                            "S0=", (example.x[s0].text if s0 >= 0 else "__"),
+                            "B0=", (example.x[b0].text if b0 >= 0 else "__"),
+                            "S0 head?", str(state.has_head(state.S(0))),
+                        )))
                     action.do(state.c, action.label)
                     break
             else:
-                print("Actions")
-                for i in range(self.n_moves):
-                    print(self.get_class_name(i))
-                print("Gold")
-                for token in example.y:
-                    print(token.text, token.dep_, token.head.text)
-                s0 = state.S(0)
-                b0 = state.B(0)
-                debug_log.append(" ".join((
-                    "?",
-                    "S0=", (example.x[s0].text if s0 >= 0 else "-"),
-                    "B0=", (example.x[b0].text if b0 >= 0 else "-"),
-                    "S0 head?", str(state.has_head(state.S(0))),
-                )))
-                print("\n".join(debug_log))
+                if _debug:
+                    print("Actions")
+                    for i in range(self.n_moves):
+                        print(self.get_class_name(i))
+                    print("Gold")
+                    for token in example.y:
+                        print(token.text, token.dep_, token.head.text)
+                    s0 = state.S(0)
+                    b0 = state.B(0)
+                    debug_log.append(" ".join((
+                        "?",
+                        "S0=", (example.x[s0].text if s0 >= 0 else "-"),
+                        "B0=", (example.x[b0].text if b0 >= 0 else "-"),
+                        "S0 head?", str(state.has_head(state.S(0))),
+                    )))
+                    print("\n".join(debug_log))
                 raise ValueError(Errors.E024)
         return history