Wrap UnexpectedCharacters error in as ObservationConfigError

src/ert/parsing/new_observations_parser.py

@@ -3,7 +3,7 @@
 from enum import Enum, auto
 from typing import Any, Dict, List, Literal, Tuple, TypedDict, Union
 
-from lark import Lark, Transformer
+from lark import Lark, Transformer, UnexpectedCharacters
 from typing_extensions import NotRequired
 
 from .config_errors import ConfigValidationError
@@ -105,9 +105,28 @@ def _parse_content(
         Tuple[ObservationType, FileContextToken, Dict[FileContextToken, Any]],
     ]
 ]:
-    return (FileContextTransformer(filename) * TreeToObservations()).transform(
-        observations_parser.parse(content)
-    )
+    try:
+        return (FileContextTransformer(filename) * TreeToObservations()).transform(
+            observations_parser.parse(content)
+        )
+    except UnexpectedCharacters as e:
+        unexpected_char = e.char
+        allowed_chars = e.allowed
+        message = (
+            f"Observation parsing failed: Did not expect character: {unexpected_char}. "
+            f"Expected one of {allowed_chars}"
+        )
+
+        raise ObservationConfigError.from_info(
+            ErrorInfo(
+                filename=filename,
+                message=message,
+                line=e.line,
+                end_line=e.line + 1,
+                column=e.column,
+                end_column=e.column + 1,
+            )
+        )
 
 
 observations_parser = Lark(

tests/test_config_parsing/test_new_observations_parser.py

@@ -1,4 +1,10 @@
-from ert.parsing.new_observations_parser import ObservationType, _parse_content
+import pytest
+
+from ert.parsing.new_observations_parser import (
+    ObservationConfigError,
+    ObservationType,
+    _parse_content,
+)
 
 
 def test_parse():
@@ -68,3 +74,44 @@ def test_parse():
             ),
         ]
     )
+
+
+def test_parse_include_outside_raises_obsconf_error():
+    with pytest.raises(
+        ObservationConfigError,
+        match="Observation parsing failed: Did not expect character",
+    ):
+        _parse_content(
+            """
+            include a;
+        HISTORY_OBSERVATION FOPR;
+
+        SUMMARY_OBSERVATION WOPR_OP1_9
+        {
+            VALUE   = 0.1;
+            ERROR   = 0.05;
+            DATE    = 2010-03-31;  -- (RESTART = 9)
+            KEY     = WOPR:OP1;
+        };
+
+        GENERAL_OBSERVATION WPR_DIFF_1 {
+           DATA       = SNAKE_OIL_WPR_DIFF;
+           INDEX_LIST = 400,800,1200,1800;
+           DATE       = 2015-06-13;  -- (RESTART = 199)
+           OBS_FILE   = wpr_diff_obs.txt;
+        };
+
+        HISTORY_OBSERVATION  FOPR
+        {
+           ERROR      = 0.1;
+
+           SEGMENT SEG
+           {
+              START = 1;
+              STOP  = 0;
+              ERROR = -1;
+           };
+        };
+    """,
+            "",
+        )