Merge pull request #628 from ChrisCummins/feature/observation-space-s…

…pec-errors

[core] Better error message is proto is invalid.

compiler_gym/views/observation_space_spec.py

@@ -4,12 +4,11 @@
 # LICENSE file in the root directory of this source tree.
 from typing import Any, Callable, ClassVar, Optional, Union
 
-# import networkx as nx
-# import numpy as np
 from gym.spaces import Space
 
 from compiler_gym.service.proto import Event, ObservationSpace, py_converters
 from compiler_gym.util.gym_type_hints import ObservationType
+from compiler_gym.util.shell_format import indent
 
 
 class ObservationSpaceSpec:
@@ -95,10 +94,34 @@ def __eq__(self, rhs) -> bool:
 
     @classmethod
     def from_proto(cls, index: int, proto: ObservationSpace):
+        """Create an observation space from a ObservationSpace protocol buffer.
+
+        :param index: The index of this observation space into the list of
+            observation spaces that the compiler service supports.
+
+        :param proto: An ObservationSpace protocol buffer.
+
+        :raises ValueError: If protocol buffer is invalid.
+        """
+        try:
+            spec = ObservationSpaceSpec.message_converter(proto.space)
+        except ValueError as e:
+            raise ValueError(
+                f"Error interpreting description of observation space '{proto.name}'.\n"
+                f"Error: {e}\n"
+                f"ObservationSpace message:\n"
+                f"{indent(proto.space, n=2)}"
+            ) from e
+
+        # TODO(cummins): Additional validation of the observation space
+        # specification would be useful here, such as making sure that the size
+        # of {low, high} tensors for box shapes match. At present, these errors
+        # tend not to show up until later, making it more difficult to debug.
+
         return cls(
             id=proto.name,
             index=index,
-            space=ObservationSpaceSpec.message_converter(proto.space),
+            space=spec,
             translate=ObservationSpaceSpec.message_converter,
             to_string=str,
             deterministic=proto.deterministic,