[AURON #2229] Silent fallback to empty partitions may cause data loss

[guixiaowen]

… #2229

Which issue does this PR close?

Closes #2229

Rationale for this change

The current implementation silently falls back to Seq.empty when both DataSource V2 and reflective partition retrieval fail. This may lead to empty input partitions without any failure signal, potentially causing silent data loss or empty query results.

Problem Description

In inputPartitions(exec: BatchScanExec), when partition planning fails:

V2 API failure → caught and ignored
Reflection failure → caught and ignored
Final fallback → Seq.empty

catch { case t: Throwable => logWarning(...) Seq.empty }

and

catch { case t: Throwable => logWarning(...) Seq.empty }

Risk

Returning an empty partition list is dangerous because:

1. Silent data loss
   Downstream execution may interpret empty partitions as:

2. no data available
   valid empty scan result

→ leads to incorrect empty query results without failure

Hard to detect in production
Only warning logs are emitted
No exception or job failure
Easy to miss in large pipelines

3. Misleading semantics
   A scan failure (cannot plan partitions) is semantically different from:

dataset is actually empty

But both are currently indistinguishable.

What changes are included in this PR?

Expected Behavior

When both:

V2 planInputPartitions
reflection-based partition retrieval

fail, the system should:

Fail fast with a clear exception:

throw new IllegalStateException( s"Failed to plan input partitions for ${exec.getClass.getName}")

Are there any user-facing changes?

Nothing.

How was this patch tested?

Depends on existing unit tests.

[ShreyeshArangath]

Since we are throwing an exception anyways, do we need to catch it in L189?