Error when removing a matcher rule that doesn't exist (#4420)

* raise specific error when removing a matcher rule that doesn't exist

* rephrasing

spacy/errors.py

@@ -498,6 +498,7 @@ class Errors(object):
             "details: https://spacy.io/api/lemmatizer#init")
     E174 = ("Architecture '{name}' not found in registry. Available "
             "names: {names}")
+    E175 = ("Can't remove rule for unknown match pattern ID: {key}")
 
 
 @add_codes

spacy/matcher/matcher.pyx

@@ -133,9 +133,11 @@ cdef class Matcher:
 
         key (unicode): The ID of the match rule.
         """
-        key = self._normalize_key(key)
+        norm_key = self._normalize_key(key)
-        self._patterns.pop(key)
+        if not norm_key in self._patterns:
-        self._callbacks.pop(key)
+            raise ValueError(Errors.E175.format(key=key))
+        self._patterns.pop(norm_key)
+        self._callbacks.pop(norm_key)
         cdef int i = 0
         while i < self.patterns.size():
             pattern_key = get_ent_id(self.patterns.at(i))

spacy/tests/matcher/test_matcher_logic.py

@@ -143,3 +143,18 @@ def test_matcher_sets_return_correct_tokens(en_vocab):
     matches = matcher(doc)
     texts = [Span(doc, s, e, label=L).text for L, s, e in matches]
     assert texts == ["zero", "one", "two"]
+
+
+def test_matcher_remove(en_vocab):
+    matcher = Matcher(en_vocab)
+    pattern = [{"ORTH": "test"}, {"OP": "?"}]
+    assert len(matcher) == 0
+    matcher.add("Rule", None, pattern)
+    assert "Rule" in matcher
+
+    # removing once should work
+    matcher.remove("Rule")
+
+    # removing again should throw an error
+    with pytest.raises(ValueError):
+        matcher.remove("Rule")