WIP: [fix] make getVectorFunction return nullptr instead of throwing exception in case of result type mismatch

[markjin1990]

What problem does this PR solve?

Issue Number: close #247

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 🚀 Performance improvement (optimization)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)
• 🔨 Refactoring (no logic changes)
• 🔧 Build/CI or Infrastructure changes
• 📝 Documentation only

Description

The function repeat(VARCHAR, INTEGER) can both be scalar function and return VARCHAR, and be vector function and return ARRAY(VARCHAR). Current compileRewrittenExpression will crash immediately when it first finds a vector function registration for repeat(VARCHAR, INTEGER) with return type ARRAY(VARCHAR) when the function repeat itself is in fact a scalar function in the following SQL.
'''
SELECT num,
row_number() OVER (
PARTITION BY
num
ORDER BY
num
) AS idx
FROM (
SELECT 1 AS NUM
UNION
SELECT 2 AS NUM
) LATERAL VIEW explode(split(repeat(',', num -1), ',')) row_repeat
'''

Performance Impact

• No Impact: This change does not affect the critical path (e.g., build system, doc, error handling).

• Positive Impact: I have run benchmarks.

  Click to view Benchmark Results

  Paste your google-benchmark or TPC-H results here.
  Before: 10.5s
  After:   8.2s  (+20%)
  

• Negative Impact: Explained below (e.g., trade-off for correctness).

Release Note

Please describe the changes in this PR

Release Note:

Release Note:
-  Fixed getVectorFunction return nullptr instead of throwing exception in case of result type mismatch

Checklist (For Author)

• I have added/updated unit tests (ctest).
• I have verified the code with local build (Release/Debug).
• I have run clang-format / linters.
• (Optional) I have run Sanitizers (ASAN/TSAN) locally for complex C++ changes.
• No need to test or manual test.

Breaking Changes

• No

• Yes (Description: ...)

  Click to view Breaking Changes

  Breaking Changes:
  - Description of the breaking change.
  - Possible solutions or workarounds.
  - Any other relevant information.