Joe/quickstart tweaks

docs/source/examples.rst

@@ -137,7 +137,7 @@ Datasets
 --------
 
 You can wrap any layer (include layer set) as a Pytorch dataset.
-In this example we will make a dataset out of the followign layer set:
+In this example we will make a dataset out of the following layer set:
 
 .. doctest::
 

docs/source/subchunkable_apply_flow_quick_start_guide.rst

@@ -385,7 +385,7 @@ CUE Files
 
 With the builder, a dictionary is all we need to specify a function call. The dictionary can be specified in any structured language, CUE
 
-``zetta_utils`` uses **CUE** files for configuring a run. CUE is an open-source data validation language that is a superset of JSON.
+``zetta_utils`` uses **CUE** files for configuring a run. `CUE <https://cuelang.org/>`_ is an open-source data validation language that is a superset of JSON.  To proceed with this tutorial, be sure you have cuelang `installed <https://cuelang.org/docs/install/>`_.
 
 .. collapse:: Why not just use Python or JSON?
 

zetta_utils/parsing/cue.py

@@ -1,6 +1,7 @@
 """cuelang parsing."""
 import os
 import pathlib
+import shutil
 import subprocess
 import tempfile
 
@@ -24,6 +25,11 @@ def loads(s: str):
 
 
 def load_local(local_path: str):
+    if shutil.which(cue_exe) is None:  # pragma: no cover
+        raise RuntimeError(
+            f"{cue_exe} not found.  Please ensure cuelang is installed ( https://cuelang.org/ )"
+        )
+
     local_path_str = _to_str_path(local_path)
     command_result = subprocess.run(
         [cue_exe, "export", local_path_str], capture_output=True, check=False