File not found exception

CHANGELOG.md

@@ -37,6 +37,7 @@ release.
 
 ### Changed
 - Reduced linescan ISD ephemeris sampling from one-per-line to every 10th line for images with 1000+ lines, significantly reducing ISD file sizes and load times for large sensors. Configurable via `reduction` and `ephem_sample_rate` props. [#677](https://github.com/DOI-USGS/ale/pull/677)
+- Throw error when input file does not exist. [#692](https://github.com/DOI-USGS/ale/pull/692)
 
 ### Fixed
 - Fixed Eigen 5.x compatibility by removing version constraint in CMakeLists.txt [#677](https://github.com/DOI-USGS/ale/pull/677)

ale/drivers/__init__.py

@@ -9,6 +9,7 @@
 import json
 import numpy as np
 import os
+import os.path
 import traceback
 from ale.base import WrongInstrumentException, WrongLabelTypeException
 import logging
@@ -128,6 +129,12 @@ def load(label, props={}, formatter='ale', verbose=False, only_isis_spice=False,
     drivers = chain.from_iterable(driver_list)
     drivers = sort_drivers([d[1] for d in drivers])
 
+    if not os.path.isfile(label):
+        raise FileNotFoundError('File "' + label + '" not found. \n' + 
+                                'Current Working Directory: "' + os.getcwd() + 
+                                '". \nMake sure your cube is present in your working directory, ' +
+                                'or that you specify the full and correct path to your cube.')
+
     if verbose:
         logger.info("Attempting to pre-parse label file")
     try: