`Builder.build()` masks plugin import failures as "template not found"

[BenWibking]

Bug: Builder.build() masks plugin import failures as "template not found"

Severity

Medium

Summary

Builder.build() catches any ImportError from __import__(...) and reports that the template does not exist. This also catches genuine plugin import/runtime dependency errors, leading to misleading diagnostics.

Impact

• Real plugin bugs appear as false "template not found" errors.
• Debugging broken plugin dependencies is harder.

Affected Code

• src/jaff/builder.py

Root Cause

Broad except ImportError conflates module-not-found and import-time failure inside plugin.

Proposed Fix

Resolve plugin module existence up front using importlib.util.find_spec. If it exists, import errors should propagate normally.

Full Patch

diff --git a/src/jaff/builder.py b/src/jaff/builder.py
index 1f12f42..8b5df3f 100644
--- a/src/jaff/builder.py
+++ b/src/jaff/builder.py
@@ -1,3 +1,4 @@
+import importlib.util
 import os
 import sys
@@ -21,15 +22,15 @@ class Builder:
 
         # import module based on the template name
-        try:
-            module = __import__(f"jaff.plugins.{template}.plugin", fromlist=["main"])
-        except ImportError as e:
+        module_name = f"jaff.plugins.{template}.plugin"
+        if importlib.util.find_spec(module_name) is None:
             print(f"Error: Template '{template}' not found. Available templates are:")
             for template in os.listdir(
                 os.path.join(os.path.dirname(__file__), "templates", "preprocessor")
             ):
                 print(template)
             sys.exit(1)
+
+        module = __import__(module_name, fromlist=["main"])
 
         # call the main function of the module to preprocess the files
         # the definition of the main function is in the plugin folder