chore: log swallowed exceptions in _partial_resolve at debug level

_partial_resolve and _partial_resolve_find_in_map intentionally substitute
AWS::NoValue / partial args for false-condition resources when the
resolver raises. The swallow matches the Kotlin reference implementation
and is not changing.

The problem is debuggability: if a resolver bug or unexpected type slips
through, the swallow hides it and the user sees a template with
AWS::NoValue substitutions that look intentional. Adding LOG.debug with
exc_info=True surfaces the traceback under --debug and in telemetry
without changing any runtime behavior.

Three swallow sites covered:
- Ref substitution fallback
- Generic Fn::* substitution fallback
- Fn::FindInMap secondary fallback inside _partial_resolve_find_in_map

The Re-raised InvalidTemplateException branch in
_partial_resolve_find_in_map is unchanged — that path must error.

Author: bnusunny

samcli/lib/cfn_language_extensions/api.py

@@ -231,13 +231,23 @@ def _partial_resolve(self, value: Any) -> Any:
                     try:
                         return self._resolver.resolve_value(value)
                     except (InvalidTemplateException, UnresolvableReferenceError, KeyError, ValueError, TypeError):
+                        LOG.debug(
+                            "Partial-resolve: substituting AWS::NoValue for unresolvable Ref %r",
+                            inner_value,
+                            exc_info=True,
+                        )
                         return {"Ref": "AWS::NoValue"}
 
                 elif key.startswith("Fn::") or key == "Condition":
                     # Try to resolve it
                     try:
                         return self._resolver.resolve_value(value)
                     except (InvalidTemplateException, UnresolvableReferenceError, KeyError, ValueError, TypeError):
+                        LOG.debug(
+                            "Partial-resolve: could not resolve %s; falling back to partial args",
+                            key,
+                            exc_info=True,
+                        )
                         # Can't resolve - replace unresolvable parts with AWS::NoValue
                         if key == "Fn::FindInMap":
                             # FindInMap - try to partially resolve arguments
@@ -310,6 +320,12 @@ def _partial_resolve_find_in_map(self, value: Dict[str, Any]) -> Any:
                 raise
             except Exception:
                 # Other errors - return with partially resolved args
+                LOG.debug(
+                    "Partial-resolve Fn::FindInMap: unexpected error resolving %r; "
+                    "returning partially-resolved args",
+                    resolved_args,
+                    exc_info=True,
+                )
                 return {"Fn::FindInMap": resolved_args}
 
         # Some args are not strings - return with partially resolved args