fix(autofix): correctly apply autofix in various conditions

- Apply autofixes after adjusting plurals. This way the fixer gets a
  correct number of plurals.
- Gracefully handle different number of plurals as these might not be
  plurals, but multi value strings.

Fixes WEBLATE-12CM
Fixes WEBLATE-1CZ9

docs/changes.rst

@@ -12,6 +12,7 @@ Not yet released.
 **Bug fixes**
 
 * Avoid query parser crash in multi-threaded environments.
+* Avoid :ref:`autofix` crash on multi-value strings.
 
 **Compatibility**
 

weblate/trans/autofixes/base.py

@@ -45,15 +45,19 @@ def fix_target(self, target: str, unit: Unit) -> tuple[list[str], bool]:
                 for number, examples in source_plural.examples.items()
             }
             target_examples = target_plural.examples
-            plurals_map = [
-                source_examples.get(tuple(target_examples.get(target_index, [])), -1)
+            plurals_map: dict[int, int] = {
+                target_index: source_examples.get(
+                    tuple(target_examples.get(target_index, [])), -1
+                )
                 for target_index in range(target_plural.number)
-            ]
+            }
             # Ensure we have a source strings for each map
             while len(source_strings) <= max(plurals_map):
                 source_strings.append(source_strings[0])
             results = [
-                self.fix_single_target(text, source_strings[plurals_map[i]], unit)
+                self.fix_single_target(
+                    text, source_strings[plurals_map.get(i, -1)], unit
+                )
                 for i, text in enumerate(target)
             ]
         return [r[0] for r in results], max(r[1] for r in results)

weblate/trans/models/unit.py

@@ -1564,10 +1564,6 @@ def translate(
         if isinstance(new_target, str):
             new_target = [new_target]
 
-        # Apply autofixes
-        if not self.translation.is_template:
-            new_target, self.fixups = fix_target(new_target, self)
-
         # Handle managing alternative translations
         if add_alternative:
             new_target.append("")
@@ -1579,6 +1575,10 @@ def translate(
         if not component.is_multivalue:
             new_target = self.adjust_plurals(new_target)
 
+        # Apply autofixes
+        if not self.translation.is_template:
+            new_target, self.fixups = fix_target(new_target, self)
+
         # Update unit and save it
         self.target = join_plural(new_target)
         not_empty = any(new_target)