Improve COCO parsing error messages (#684)

* Improve error messages in COCO format

* Fix typo

* Add quotes to error messages

* Fix message

* Remove extra type from annotations

* Split polygon points check

* Use f style for most messages

* Add mask size value count check

* Prohibit float values in size

* Extract commond annotation template in error tests

* Rename invalid label to undeclared label

* Add validators and docs, update error hierarchy

* Add overloads to parse_field

* Add score field type test

datumaro/components/errors.py

@@ -2,9 +2,11 @@
 #
 # SPDX-License-Identifier: MIT
 
-from typing import Any, Tuple
+from typing import Any, Optional, Tuple
 
-from attrs import define, field
+from attrs import define, field, validators
+
+from datumaro.util.attrs_util import has_length, not_empty
 
 
 class ImmutableObjectError(Exception):
@@ -197,21 +199,75 @@ class DatasetImportError(DatumaroError):
     pass
 
 
+class InvalidAnnotationError(DatasetImportError):
+    """
+    A basic dataset parsing error. Should include the problem description in
+    the message.
+    """
+
+
+@define(auto_exc=False)
+class InvalidFieldError(InvalidAnnotationError):
+    name: str = field(validator=[validators.instance_of(str), not_empty])
+    """Field name"""
+
+    def __str__(self) -> str:
+        return f"Invalid annotation field '{self.name}' value"
+
+
+@define(auto_exc=False)
+class InvalidFieldTypeError(InvalidFieldError):
+    actual: str = field(validator=[validators.instance_of(str), not_empty])
+    """Actual type of the field"""
+
+    expected: Tuple[str] = field(validator=[validators.instance_of(tuple), not_empty])
+    """The list of expected types of the field"""
+
+    def __str__(self) -> str:
+        if len(self.expected) == 1:
+            expected = self.expected[0]
+        else:
+            expected = "one of " + ", ".join(self.expected)
+        return f"Invalid annotation field '{self.name}' type '{self.actual}'. Expected '{expected}'"
+
+
+@define(auto_exc=False)
+class MissingFieldError(InvalidFieldError):
+    def __str__(self) -> str:
+        return f"Missing annotation field '{self.name}'"
+
+
+@define(auto_exc=False)
+class UndeclaredLabelError(InvalidAnnotationError):
+    id: str = field(validator=validators.instance_of(str))
+    """Index or name"""
+
+    def __str__(self) -> str:
+        return f"Undeclared label '{self.id}'"
+
+
 @define(auto_exc=False)
 class ItemImportError(DatasetImportError):
     """
-    Represents additional item error info. The error itself is supposed to be
-    in the `__cause__` member.
+    Wraps a dataset parsing error and provides additional error context info.
+    The error itself is supposed to be in the `__cause__` member.
     """
 
-    item_id: Tuple[str, str]
+    item_id: Tuple[Optional[str], Optional[str]] = field(
+        validator=[validators.instance_of(tuple), has_length(2)]
+    )
+    """
+    (id, subset) of the item with problem.
+    If id or subset cannot be reported, such field is set to None.
+    """
 
     def __str__(self):
-        return "Failed to import item %s" % (self.item_id,)
+        return f"Failed to import item {self.item_id}"
 
 
 class AnnotationImportError(ItemImportError):
-    pass
+    def __str__(self):
+        return f"Failed to import item {self.item_id} annotation"
 
 
 @define(auto_exc=False)