From 4cbf0d3bb603c96630c289115a37bacaa126a289 Mon Sep 17 00:00:00 2001
From: Matthew Honnibal <honnibal+gh@gmail.com>
Date: Tue, 27 Sep 2016 19:19:53 +0200
Subject: [PATCH] Handle errors when no valid actions are available, pointing
 users to the issue tracker.

---
 spacy/syntax/parser.pyx | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/spacy/syntax/parser.pyx b/spacy/syntax/parser.pyx
index 842a06a23..a8f1973af 100644
--- a/spacy/syntax/parser.pyx
+++ b/spacy/syntax/parser.pyx
@@ -113,7 +113,7 @@ cdef class Parser:
         # Check for KeyboardInterrupt etc. Untested
         PyErr_CheckSignals()
         if status != 0:
-            raise ValueError("Error parsing doc: %s" % tokens.text)
+            raise ParserStateError(tokens)
         self.moves.finalize_doc(tokens)
 
     def pipe(self, stream, int batch_size=1000, int n_threads=2):
@@ -136,8 +136,7 @@ cdef class Parser:
                         status = self.parseC(doc_ptr[i], lengths[i], nr_feat, nr_class)
                         if status != 0:
                             with gil:
-                                sent_str = queue[i].text
-                                raise ValueError("Error parsing doc: %s" % sent_str)
+                                raise ParserStateError(queue[i])
                 PyErr_CheckSignals()
                 for doc in queue:
                     self.moves.finalize_doc(doc)
@@ -149,8 +148,7 @@ cdef class Parser:
                 status = self.parseC(doc_ptr[i], lengths[i], nr_feat, nr_class)
                 if status != 0:
                     with gil:
-                        sent_str = queue[i].text
-                        raise ValueError("Error parsing doc: %s" % sent_str)
+                        raise ParserStateError(queue[i])
         PyErr_CheckSignals()
         for doc in queue:
             self.moves.finalize_doc(doc)
@@ -307,6 +305,17 @@ cdef class StepwiseState:
         self.parser.moves.finalize_doc(self.doc)
 
 
+class ParserStateError(ValueError):
+    def __repr__(self):
+        raise ValueError(
+            "Error analysing doc -- no valid actions available. This should "
+            "never happen, so please report the error on the issue tracker. "
+            "Here's the thread to do so --- reopen it if it's closed:\n"
+            "https://github.com/spacy-io/spaCy/issues/429\n"
+            "Please include the text that the parser failed on, which is:\n"
+            "%s" % repr(self.args[0].text))
+
+
 cdef int _arg_max_clas(const weight_t* scores, int move, const Transition* actions,
                        int nr_class) except -1:
     cdef weight_t score = 0