Better error when app version is not found

bfabric_app_runner/docs/changelog.md

@@ -10,6 +10,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
     symlinks instead of copying the file, as needed.
 - `BfabricOrderFastaSpec.required` which allows specifying whether the order fasta is required or not
 
+### Changed
+
+- Better error when app version is not found.
+
 ## \[0.0.14\] - 2025-01-30
 
 ### Fixed

bfabric_app_runner/src/bfabric_app_runner/app_runner/resolve_app.py

@@ -22,6 +22,14 @@ def resolve_app(versions: AppSpec, workunit_definition: WorkunitDefinition) -> A
         raise ValueError("The workunit definition does not contain an application version.")
     app_version = workunit_definition.execution.raw_parameters["application_version"]
     # TODO graceful handling of invalid versions
+    if app_version in versions and versions[app_version] is not None:
+        return app_version
+    else:
+        msg = (
+            f"application_version '{app_version}' is not defined in the app spec,\n"
+            f" available versions: {sorted(versions.keys())}"
+        )
+        raise ValueError(msg)
     return versions[app_version]