Fix issue with overlapping formatting (#2012)

novelwriter/core/tokenizer.py

@@ -1150,8 +1150,9 @@ class Tokenizer(ABC):
         formats = []
         for pos, n, fmt, key in reversed(sorted(temp, key=lambda x: x[0])):
             if fmt > 0:
-                result = result[:pos] + result[pos+n:]
-                formats = [(p-n, f, k) for p, f, k in formats]
+                if n > 0:
+                    result = result[:pos] + result[pos+n:]
+                    formats = [(p-n if p > pos else p, f, k) for p, f, k in formats]
                 formats.insert(0, (pos, fmt, key))
 
         return result, formats

tests/test_core/test_core_tokenizer.py

@@ -1161,6 +1161,24 @@ def testCoreToken_Dialogue(mockGUI):
         Tokenizer.A_NONE
     )]
 
+    # Special Cases
+    # =============
+
+    # Dialogue + formatting on same index (Issue #2012)
+    tokens._text = "[i]\u201cDialogue text.\u201d[/i]\n"
+    tokens.tokenizeText()
+    assert tokens._tokens == [(
+        Tokenizer.T_TEXT, 0,
+        "\u201cDialogue text.\u201d",
+        [
+            (0,  Tokenizer.FMT_I_B, ""),
+            (0,  Tokenizer.FMT_DL_B, ""),
+            (16, Tokenizer.FMT_I_E, ""),
+            (16, Tokenizer.FMT_DL_E, ""),
+        ],
+        Tokenizer.A_NONE
+    )]
+
 
 @pytest.mark.core
 def testCoreToken_SpecialFormat(mockGUI):